diff --git a/src/Data/UserDataStore.cs b/src/Data/UserDataStore.cs
index b21eb73..661d398 100644
--- a/src/Data/UserDataStore.cs
+++ b/src/Data/UserDataStore.cs
@@ -92,6 +92,24 @@ public class UserDataStore(DarkMasterMemoryDatabase masterDb)
     public bool TryGet(long userId, out DarkUserMemoryDatabase db)
         => _users.TryGetValue(userId, out db!);
 
+    /// <summary>
+    /// Finds the user database whose EntityIUser record matches the given playerId.
+    /// Returns false if no user has that playerId.
+    /// </summary>
+    public bool TryGetByPlayerId(long playerId, out DarkUserMemoryDatabase db)
+    {
+        foreach (var (_, userDb) in _users)
+        {
+            if (userDb.EntityIUser.Any(u => u.PlayerId == playerId))
+            {
+                db = userDb;
+                return true;
+            }
+        }
+        db = null!;
+        return false;
+    }
+
     /// <summary>
     /// Stores a user database, replacing any existing one for that userId.
     /// </summary>
diff --git a/src/Services/UserService.cs b/src/Services/UserService.cs
index d45afb0..c0b8bc5 100644
--- a/src/Services/UserService.cs
+++ b/src/Services/UserService.cs
@@ -11,6 +11,9 @@ namespace MariesWonderland.Services;
 
 public class UserService(UserDataStore store, UserDataSeeder seeder) : MariesWonderland.Proto.User.UserService.UserServiceBase
 {
+    public const string AndroidApiKey = "1234567890";
+    public const string AndroidNonce = "Mama";
+
     private readonly UserDataStore _store = store;
     private readonly UserDataSeeder _seeder = seeder;
 
@@ -19,8 +22,8 @@ public class UserService(UserDataStore store, UserDataSeeder seeder) : MariesWon
     {
         return Task.FromResult(new GetAndroidArgsResponse
         {
-            ApiKey = "1234567890",
-            Nonce = "Mama"
+            ApiKey = AndroidApiKey,
+            Nonce = AndroidNonce
         });
     }
 
@@ -166,41 +169,33 @@ public class UserService(UserDataStore store, UserDataSeeder seeder) : MariesWon
     /// <summary>Returns a player's profile including name, level, favorite costume, and lead deck character.</summary>
     public override Task<GetUserProfileResponse> GetUserProfile(GetUserProfileRequest request, ServerCallContext context)
     {
-        long userId = request.PlayerId != 0 ? request.PlayerId : context.GetUserId();
+        long callerUserId = context.GetUserId();
 
-        if (!_store.TryGet(userId, out DarkUserMemoryDatabase userDb))
-        {
-            return Task.FromResult(new GetUserProfileResponse
-            {
-                LatestUsedDeck = new ProfileDeck { Power = 100 },
-                PvpInfo = new ProfilePvpInfo(),
-                GamePlayHistory = new GamePlayHistory
-                {
-                    HistoryItem = { },
-                    HistoryCategoryGraphItem = { }
-                }
-            });
-        }
+        if (!_store.TryGetByPlayerId(request.PlayerId, out DarkUserMemoryDatabase targetDb))
+            return Task.FromResult(new GetUserProfileResponse());
 
-        EntityIUserProfile? profile = userDb.EntityIUserProfile.FirstOrDefault(p => p.UserId == userId);
-        EntityIUserStatus? status = userDb.EntityIUserStatus.FirstOrDefault(s => s.UserId == userId);
+        EntityIUserProfile? profile = targetDb.EntityIUserProfile.FirstOrDefault(p => p.UserId == targetDb.UserId);
+        EntityIUserStatus? status = targetDb.EntityIUserStatus.FirstOrDefault(s => s.UserId == targetDb.UserId);
+        bool isOwnProfile = targetDb.UserId == callerUserId;
+        int maxDeckPower = 0;
 
         List<ProfileDeckCharacter> deckCharacters = [];
 
-        EntityIUserDeck? deck = userDb.EntityIUserDeck.FirstOrDefault(d =>
+        EntityIUserDeck? deck = targetDb.EntityIUserDeck.FirstOrDefault(d =>
             d.DeckType == DeckType.QUEST && d.UserDeckNumber == 1);
 
         if (deck != null && !string.IsNullOrEmpty(deck.UserDeckCharacterUuid01))
         {
-            EntityIUserDeckCharacter? dc = userDb.EntityIUserDeckCharacter
+            EntityIUserDeckCharacter? dc = targetDb.EntityIUserDeckCharacter
                 .FirstOrDefault(c => c.UserDeckCharacterUuid == deck.UserDeckCharacterUuid01);
 
             if (dc != null)
             {
-                int costumeId = userDb.EntityIUserCostume
+                maxDeckPower = dc.Power;
+                int costumeId = targetDb.EntityIUserCostume
                     .FirstOrDefault(c => c.UserCostumeUuid == dc.UserCostumeUuid)?.CostumeId ?? 0;
 
-                EntityIUserWeapon? weapon = userDb.EntityIUserWeapon
+                EntityIUserWeapon? weapon = targetDb.EntityIUserWeapon
                     .FirstOrDefault(w => w.UserWeaponUuid == dc.MainUserWeaponUuid);
 
                 deckCharacters.Add(new ProfileDeckCharacter
@@ -215,16 +210,22 @@ public class UserService(UserDataStore store, UserDataSeeder seeder) : MariesWon
         return Task.FromResult(new GetUserProfileResponse
         {
             Level = status?.Level ?? 0,
-            Name = profile?.Name ?? "",
+            Name = profile?.Name ?? string.Empty,
             FavoriteCostumeId = profile?.FavoriteCostumeId ?? 0,
-            Message = profile?.Message ?? "",
+            Message = profile?.Message ?? string.Empty,
             IsFriend = false,
             LatestUsedDeck = new ProfileDeck
             {
-                Power = 100,
+                Power = maxDeckPower,
                 DeckCharacter = { deckCharacters }
             },
-            PvpInfo = new ProfilePvpInfo(),
+            PvpInfo = new ProfilePvpInfo()
+            {
+                MaxSeasonRank = targetDb.EntityIUserPvpWeeklyResult
+                    .GroupBy(x => x.PvpSeasonId)
+                    .DefaultIfEmpty()
+                    .Min(x => x?.OrderBy(y => y.PvpWeeklyVersion).Select(y => y.FinalRank).LastOrDefault() ?? 0),
+            },
             GamePlayHistory = new GamePlayHistory
             {
                 HistoryItem = { },
diff --git a/tests/Services/UserServiceTests.cs b/tests/Services/UserServiceTests.cs
new file mode 100644
index 0000000..1b5f468
--- /dev/null
+++ b/tests/Services/UserServiceTests.cs
@@ -0,0 +1,411 @@
+using Google.Protobuf.WellKnownTypes;
+using MariesWonderland.Configuration;
+using MariesWonderland.Data;
+using MariesWonderland.Models.Entities;
+using MariesWonderland.Models.Type;
+using MariesWonderland.Proto.User;
+using MariesWonderland.Tests.Infrastructure;
+using Microsoft.Extensions.Options;
+using UserService = MariesWonderland.Services.UserService;
+
+namespace MariesWonderland.Tests.Services;
+
+public class UserServiceTests(MasterDatabaseFixture fixture) : ServiceTestBase(fixture), IClassFixture<MasterDatabaseFixture>
+{
+    private const long UserId = 1L;
+
+    private static UserService CreateService(UserDataStore store)
+    {
+        var options = Options.Create(new ServerOptions());
+        var seeder = new UserDataSeeder(options);
+        return new UserService(store, seeder);
+    }
+
+    /// <summary>
+    /// Verifies that SetUserName updates the profile name and sets the name update timestamp.
+    /// </summary>
+    [Fact]
+    public async Task SetUserName_WithExistingProfile_UpdatesNameAndTimestamp()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUserProfile.Add(new EntityIUserProfile
+        {
+            UserId = UserId,
+            Name = "OldName"
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.SetUserName(
+            new SetUserNameRequest { Name = "NewName" },
+            ContextFor(UserId));
+
+        Assert.NotNull(response);
+        Assert.Equal("NewName", userDb.EntityIUserProfile[0].Name);
+        Assert.True(userDb.EntityIUserProfile[0].NameUpdateDatetime > 0);
+    }
+
+    /// <summary>
+    /// Verifies that SetUserSetting updates the notification preference on the setting record.
+    /// </summary>
+    [Fact]
+    public async Task SetUserSetting_WithExistingSetting_UpdatesNotifyPurchaseAlert()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUserSetting.Add(new EntityIUserSetting
+        {
+            UserId = UserId,
+            IsNotifyPurchaseAlert = false
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.SetUserSetting(
+            new SetUserSettingRequest { IsNotifyPurchaseAlert = true },
+            ContextFor(UserId));
+
+        Assert.NotNull(response);
+        Assert.True(userDb.EntityIUserSetting[0].IsNotifyPurchaseAlert);
+    }
+
+    /// <summary>
+    /// Verifies that SetUserMessage updates the profile message and sets the message update timestamp.
+    /// </summary>
+    [Fact]
+    public async Task SetUserMessage_WithExistingProfile_UpdatesMessageAndTimestamp()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUserProfile.Add(new EntityIUserProfile
+        {
+            UserId = UserId,
+            Name = "TestUser"
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.SetUserMessage(
+            new SetUserMessageRequest { Message = "Hello World" },
+            ContextFor(UserId));
+
+        Assert.NotNull(response);
+        Assert.Equal("Hello World", userDb.EntityIUserProfile[0].Message);
+        Assert.True(userDb.EntityIUserProfile[0].MessageUpdateDatetime > 0);
+    }
+
+    /// <summary>
+    /// Verifies that SetUserFavoriteCostumeId updates the profile's favorite costume and timestamp.
+    /// </summary>
+    [Fact]
+    public async Task SetUserFavoriteCostumeId_WithExistingProfile_UpdatesCostumeIdAndTimestamp()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUserProfile.Add(new EntityIUserProfile
+        {
+            UserId = UserId,
+            Name = "TestUser"
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.SetUserFavoriteCostumeId(
+            new SetUserFavoriteCostumeIdRequest { FavoriteCostumeId = 42 },
+            ContextFor(UserId));
+
+        Assert.NotNull(response);
+        Assert.Equal(42, userDb.EntityIUserProfile[0].FavoriteCostumeId);
+        Assert.True(userDb.EntityIUserProfile[0].FavoriteCostumeIdUpdateDatetime > 0);
+    }
+
+    /// <summary>
+    /// Verifies that SetBirthYearMonth updates the user's birth year and month.
+    /// </summary>
+    [Fact]
+    public async Task SetBirthYearMonth_WithExistingUser_UpdatesBirthYearAndMonth()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.SetBirthYearMonth(
+            new SetBirthYearMonthRequest { BirthYear = 1990, BirthMonth = 6 },
+            ContextFor(UserId));
+
+        Assert.NotNull(response);
+        Assert.Equal(1990, userDb.EntityIUser[0].BirthYear);
+        Assert.Equal(6, userDb.EntityIUser[0].BirthMonth);
+    }
+
+    /// <summary>
+    /// Verifies that GetBirthYearMonth returns the stored birth year and month.
+    /// </summary>
+    [Fact]
+    public async Task GetBirthYearMonth_WithExistingUser_ReturnsStoredValues()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser
+        {
+            UserId = UserId,
+            BirthYear = 1985,
+            BirthMonth = 3
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetBirthYearMonth(
+            new Empty(),
+            ContextFor(UserId));
+
+        Assert.Equal(1985, response.BirthYear);
+        Assert.Equal(3, response.BirthMonth);
+    }
+
+    /// <summary>
+    /// Verifies that GetChargeMoney returns the stored charge money amount.
+    /// </summary>
+    [Fact]
+    public async Task GetChargeMoney_WithExistingSUser_ReturnsChargeMoneyThisMonth()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntitySUser.Add(new EntitySUser
+        {
+            UserId = UserId,
+            ChargeMoneyThisMonth = 500
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetChargeMoney(
+            new Empty(),
+            ContextFor(UserId));
+
+        Assert.Equal(500, response.ChargeMoneyThisMonth);
+    }
+
+    /// <summary>
+    /// Verifies that GetChargeMoney returns zero when no EntitySUser record exists.
+    /// </summary>
+    [Fact]
+    public async Task GetChargeMoney_WithNoSUser_ReturnsZero()
+    {
+        var userDb = CreateUserDb();
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetChargeMoney(
+            new Empty(),
+            ContextFor(UserId));
+
+        Assert.Equal(0, response.ChargeMoneyThisMonth);
+    }
+
+    [Fact]
+    public async Task GetUserProfile_ReturnsLevelFromStatus()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId, PlayerId = 12345L });
+        userDb.EntityIUserStatus.Add(new EntityIUserStatus { UserId = UserId, Level = 42 });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetUserProfile(
+            new GetUserProfileRequest { PlayerId = 12345L },
+            ContextFor(UserId));
+
+        Assert.Equal(42, response.Level);
+    }
+
+    [Fact]
+    public async Task GetUserProfile_ReturnsNameFromProfile()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId, PlayerId = 12345L });
+        userDb.EntityIUserProfile.Add(new EntityIUserProfile { UserId = UserId, Name = "TestPlayer" });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetUserProfile(
+            new GetUserProfileRequest { PlayerId = 12345L },
+            ContextFor(UserId));
+
+        Assert.Equal("TestPlayer", response.Name);
+    }
+
+    [Fact]
+    public async Task GetUserProfile_ReturnsFavoriteCostumeIdFromProfile()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId, PlayerId = 12345L });
+        userDb.EntityIUserProfile.Add(new EntityIUserProfile { UserId = UserId, FavoriteCostumeId = 99 });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetUserProfile(
+            new GetUserProfileRequest { PlayerId = 12345L },
+            ContextFor(UserId));
+
+        Assert.Equal(99, response.FavoriteCostumeId);
+    }
+
+    [Fact]
+    public async Task GetUserProfile_ReturnsMessageFromProfile()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId, PlayerId = 12345L });
+        userDb.EntityIUserProfile.Add(new EntityIUserProfile { UserId = UserId, Message = "Hello!" });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetUserProfile(
+            new GetUserProfileRequest { PlayerId = 12345L },
+            ContextFor(UserId));
+
+        Assert.Equal("Hello!", response.Message);
+    }
+
+    [Fact]
+    public async Task GetUserProfile_ReturnsPopulatedLatestUsedDeck()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId, PlayerId = 12345L });
+        userDb.EntityIUserDeck.Add(new EntityIUserDeck
+        {
+            UserId = UserId,
+            DeckType = DeckType.QUEST,
+            UserDeckNumber = 1,
+            UserDeckCharacterUuid01 = "dc-uuid"
+        });
+        userDb.EntityIUserDeckCharacter.Add(new EntityIUserDeckCharacter
+        {
+            UserId = UserId,
+            UserDeckCharacterUuid = "dc-uuid",
+            Power = 5000,
+            UserCostumeUuid = "c-uuid",
+            MainUserWeaponUuid = "w-uuid"
+        });
+        userDb.EntityIUserCostume.Add(new EntityIUserCostume
+        {
+            UserId = UserId,
+            UserCostumeUuid = "c-uuid",
+            CostumeId = 200100
+        });
+        userDb.EntityIUserWeapon.Add(new EntityIUserWeapon
+        {
+            UserId = UserId,
+            UserWeaponUuid = "w-uuid",
+            WeaponId = 300100,
+            Level = 15
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetUserProfile(
+            new GetUserProfileRequest { PlayerId = 12345L },
+            ContextFor(UserId));
+
+        Assert.Equal(5000, response.LatestUsedDeck.Power);
+        Assert.Single(response.LatestUsedDeck.DeckCharacter);
+        Assert.Equal(200100, response.LatestUsedDeck.DeckCharacter[0].CostumeId);
+        Assert.Equal(300100, response.LatestUsedDeck.DeckCharacter[0].MainWeaponId);
+        Assert.Equal(15, response.LatestUsedDeck.DeckCharacter[0].MainWeaponLevel);
+    }
+
+    [Fact]
+    public async Task GetUserProfile_ReturnsMaxSeasonRankFromPvpResults()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId, PlayerId = 12345L });
+        userDb.EntityIUserPvpWeeklyResult.Add(new EntityIUserPvpWeeklyResult
+        {
+            UserId = UserId,
+            PvpSeasonId = 1,
+            PvpWeeklyVersion = 1,
+            FinalRank = 50
+        });
+        userDb.EntityIUserPvpWeeklyResult.Add(new EntityIUserPvpWeeklyResult
+        {
+            UserId = UserId,
+            PvpSeasonId = 1,
+            PvpWeeklyVersion = 2,
+            FinalRank = 30
+        });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetUserProfile(
+            new GetUserProfileRequest { PlayerId = 12345L },
+            ContextFor(UserId));
+
+        Assert.Equal(30, response.PvpInfo.MaxSeasonRank);
+    }
+
+    [Fact]
+    public async Task GetUserProfile_UnknownPlayerId_ReturnsEmptyResponse()
+    {
+        var userDb = CreateUserDb();
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetUserProfile(
+            new GetUserProfileRequest { PlayerId = 99999L },
+            ContextFor(UserId));
+
+        Assert.Equal(string.Empty, response.Name);
+        Assert.Equal(0, response.Level);
+    }
+
+    [Fact]
+    public async Task GetAndroidArgs_ReturnsExpectedApiKeyAndNonce()
+    {
+        var store = CreateStore(UserId, CreateUserDb(), MasterDb);
+        var service = CreateService(store);
+
+        var response = await service.GetAndroidArgs(new GetAndroidArgsRequest(), ContextFor(UserId));
+
+        Assert.Equal(UserService.AndroidApiKey, response.ApiKey);
+        Assert.Equal(UserService.AndroidNonce, response.Nonce);
+    }
+
+    [Fact]
+    public async Task GameStart_SetsGameStartDatetimeOnEntityIUser()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        await service.GameStart(new Empty(), ContextFor(UserId));
+
+        Assert.True(userDb.EntityIUser[0].GameStartDatetime > 0);
+    }
+
+    [Fact]
+    public async Task GameStart_CreatesEntityIUserGemIfNoneExists()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        await service.GameStart(new Empty(), ContextFor(UserId));
+
+        Assert.Single(userDb.EntityIUserGem);
+        Assert.Equal(0, userDb.EntityIUserGem[0].PaidGem);
+        Assert.Equal(0, userDb.EntityIUserGem[0].FreeGem);
+    }
+
+    [Fact]
+    public async Task GameStart_DoesNotCreateDuplicateEntityIUserGem()
+    {
+        var userDb = CreateUserDb();
+        userDb.EntityIUser.Add(new EntityIUser { UserId = UserId });
+        userDb.EntityIUserGem.Add(new EntityIUserGem { UserId = UserId, PaidGem = 100, FreeGem = 50 });
+        var store = CreateStore(UserId, userDb, MasterDb);
+        var service = CreateService(store);
+
+        await service.GameStart(new Empty(), ContextFor(UserId));
+
+        Assert.Single(userDb.EntityIUserGem);
+        Assert.Equal(100, userDb.EntityIUserGem[0].PaidGem);
+    }
+}