diff --git a/cmd/protbot/scenario/chat.go b/cmd/protbot/scenario/chat.go
index 8e5ba64fb..76dc3dae1 100644
--- a/cmd/protbot/scenario/chat.go
+++ b/cmd/protbot/scenario/chat.go
@@ -62,8 +62,8 @@ func ListenChat(ch *protocol.ChannelConn, cb ChatCallback) {
 		_ = pbf.ReadUint16() // flags
 		_ = pbf.ReadUint16() // senderNameLen
 		_ = pbf.ReadUint16() // messageLen
-		msg, _ := stringsupport.SJISToUTF8(pbf.ReadNullTerminatedBytes())
-		sender, _ := stringsupport.SJISToUTF8(pbf.ReadNullTerminatedBytes())
+		msg := stringsupport.SJISToUTF8Lossy(pbf.ReadNullTerminatedBytes())
+		sender := stringsupport.SJISToUTF8Lossy(pbf.ReadNullTerminatedBytes())
 
 		cb(ChatMessage{
 			ChatType:   chatType,
diff --git a/common/stringsupport/string_convert.go b/common/stringsupport/string_convert.go
index 41a3dbeb0..dc7657514 100644
--- a/common/stringsupport/string_convert.go
+++ b/common/stringsupport/string_convert.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"log/slog"
 	"strconv"
 	"strings"
 
@@ -40,6 +41,16 @@ func SJISToUTF8(b []byte) (string, error) {
 	return string(result), nil
 }
 
+// SJISToUTF8Lossy decodes Shift-JIS bytes to a UTF-8 string, logging
+// any decoding error at debug level instead of returning it.
+func SJISToUTF8Lossy(b []byte) string {
+	s, err := SJISToUTF8(b)
+	if err != nil {
+		slog.Debug("SJIS decode failed", "error", err, "raw_len", len(b))
+	}
+	return s
+}
+
 // ToNGWord converts a UTF-8 string into a slice of uint16 values in the
 // Shift-JIS byte-swapped format used by the MHF NG-word (chat filter) system.
 func ToNGWord(x string) []uint16 {
diff --git a/common/stringsupport/string_convert_test.go b/common/stringsupport/string_convert_test.go
index b90582024..33e281a5f 100644
--- a/common/stringsupport/string_convert_test.go
+++ b/common/stringsupport/string_convert_test.go
@@ -461,6 +461,25 @@ func BenchmarkCSVElems(b *testing.B) {
 	}
 }
 
+func TestSJISToUTF8Lossy(t *testing.T) {
+	// Valid SJIS (ASCII subset) decodes correctly.
+	got := SJISToUTF8Lossy([]byte("Hello"))
+	if got != "Hello" {
+		t.Errorf("SJISToUTF8Lossy(valid) = %q, want %q", got, "Hello")
+	}
+
+	// Truncated multi-byte SJIS sequence (lead byte 0x82 without trail byte)
+	// does not panic and returns some result (lossy).
+	got = SJISToUTF8Lossy([]byte{0x82})
+	_ = got // must not panic
+
+	// Nil input returns empty string.
+	got = SJISToUTF8Lossy(nil)
+	if got != "" {
+		t.Errorf("SJISToUTF8Lossy(nil) = %q, want %q", got, "")
+	}
+}
+
 func TestUTF8ToSJIS_UnsupportedCharacters(t *testing.T) {
 	// Regression test for PR #116: Characters outside the Shift-JIS range
 	// (e.g. Lenny face, cuneiform) previously caused a panic in UTF8ToSJIS,
diff --git a/docs/technical-debt.md b/docs/technical-debt.md
index 9b72c85e9..a389b0ca9 100644
--- a/docs/technical-debt.md
+++ b/docs/technical-debt.md
@@ -102,17 +102,7 @@ Suggested split: `repo_guild.go` (core CRUD), `repo_guild_members.go`, `repo_gui
 
 ~~**a) `fmt.Sprintf` inside structured logger calls (6 sites):**~~ **Fixed.** All 6 sites now use `zap.Uint32`/`zap.Uint8`/`zap.String` structured fields instead of `fmt.Sprintf`.
 
-**b) 20 silently discarded SJIS encoding errors in packet parsing:**
-
-The pattern `m.Field, _ = stringsupport.SJISToUTF8(...)` appears across:
-- `network/binpacket/msg_bin_chat.go:43-44`
-- `network/mhfpacket/msg_mhf_apply_bbs_article.go:33-35`
-- `network/mhfpacket/msg_mhf_send_mail.go:38-39`
-- `network/mhfpacket/msg_mhf_update_guild_message_board.go:41-42,50-51`
-- `server/channelserver/model_character.go:175`
-- And 7+ more packet files
-
-A malformed SJIS string from a client yields an empty string with no log output, making garbled text impossible to debug. The error return should at least be logged at debug level.
+~~**b) 20+ silently discarded SJIS encoding errors in packet parsing:**~~ **Fixed.** All call sites now use `SJISToUTF8Lossy()` which logs decode errors at `slog.Debug` level.
 
 ### ~~6. Inconsistent transaction API~~ (Fixed)
 
@@ -151,5 +141,5 @@ Based on impact and the momentum from recent repo-interface refactoring:
 4. **Split `repo_guild.go`** — last oversized file after the recent refactoring push
 5. ~~**Fix `fmt.Sprintf` in logger calls**~~ — **Done**
 6. ~~**Add `LoopDelay` Viper default**~~ — **Done**
-7. **Log SJIS decoding errors** — improves debuggability for text issues
+7. ~~**Log SJIS decoding errors**~~ — **Done**
 8. ~~**Standardize on `BeginTxx`**~~ — **Done**
diff --git a/network/binpacket/msg_bin_chat.go b/network/binpacket/msg_bin_chat.go
index ebd1636cc..1068e9565 100644
--- a/network/binpacket/msg_bin_chat.go
+++ b/network/binpacket/msg_bin_chat.go
@@ -40,8 +40,8 @@ func (m *MsgBinChat) Parse(bf *byteframe.ByteFrame) error {
 	m.Flags = bf.ReadUint16()
 	_ = bf.ReadUint16() // lenSenderName
 	_ = bf.ReadUint16() // lenMessage
-	m.Message, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
-	m.SenderName, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Message = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
+	m.SenderName = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	return nil
 }
 
diff --git a/network/mhfpacket/msg_mhf_apply_bbs_article.go b/network/mhfpacket/msg_mhf_apply_bbs_article.go
index 4a83e36d3..f4e0980a2 100644
--- a/network/mhfpacket/msg_mhf_apply_bbs_article.go
+++ b/network/mhfpacket/msg_mhf_apply_bbs_article.go
@@ -30,9 +30,9 @@ func (m *MsgMhfApplyBbsArticle) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Cl
 	m.AckHandle = bf.ReadUint32()
 	m.Unk0 = bf.ReadUint32()
 	m.Unk1 = bf.ReadBytes(16)
-	m.Name, _ = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(32)))
-	m.Title, _ = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(128)))
-	m.Description, _ = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(256)))
+	m.Name = stringsupport.SJISToUTF8Lossy(bfutil.UpToNull(bf.ReadBytes(32)))
+	m.Title = stringsupport.SJISToUTF8Lossy(bfutil.UpToNull(bf.ReadBytes(128)))
+	m.Description = stringsupport.SJISToUTF8Lossy(bfutil.UpToNull(bf.ReadBytes(256)))
 	return nil
 }
 
diff --git a/network/mhfpacket/msg_mhf_create_guild.go b/network/mhfpacket/msg_mhf_create_guild.go
index a3739a184..44eb117b7 100644
--- a/network/mhfpacket/msg_mhf_create_guild.go
+++ b/network/mhfpacket/msg_mhf_create_guild.go
@@ -25,7 +25,7 @@ func (m *MsgMhfCreateGuild) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Client
 	m.AckHandle = bf.ReadUint32()
 	bf.ReadUint16() // Zeroed
 	bf.ReadUint16() // Name length
-	m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Name = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	return nil
 }
 
diff --git a/network/mhfpacket/msg_mhf_create_joint.go b/network/mhfpacket/msg_mhf_create_joint.go
index 303571548..045ae5163 100644
--- a/network/mhfpacket/msg_mhf_create_joint.go
+++ b/network/mhfpacket/msg_mhf_create_joint.go
@@ -27,7 +27,7 @@ func (m *MsgMhfCreateJoint) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Client
 	m.GuildID = bf.ReadUint32()
 	bf.ReadUint16() // Zeroed
 	bf.ReadUint16() // Name length
-	m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Name = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	return nil
 }
 
diff --git a/network/mhfpacket/msg_mhf_enumerate_house.go b/network/mhfpacket/msg_mhf_enumerate_house.go
index fa3cc30cc..f011bec7a 100644
--- a/network/mhfpacket/msg_mhf_enumerate_house.go
+++ b/network/mhfpacket/msg_mhf_enumerate_house.go
@@ -30,7 +30,7 @@ func (m *MsgMhfEnumerateHouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Cli
 	bf.ReadUint16() // Zeroed
 	lenName := bf.ReadUint8()
 	if lenName > 0 {
-		m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+		m.Name = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	}
 	return nil
 }
diff --git a/network/mhfpacket/msg_mhf_load_house.go b/network/mhfpacket/msg_mhf_load_house.go
index 029307a18..5753517c5 100644
--- a/network/mhfpacket/msg_mhf_load_house.go
+++ b/network/mhfpacket/msg_mhf_load_house.go
@@ -32,7 +32,7 @@ func (m *MsgMhfLoadHouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.ClientCo
 	m.CheckPass = bf.ReadBool()
 	bf.ReadUint16() // Zeroed
 	bf.ReadUint8()  // Password length
-	m.Password, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Password = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	return nil
 }
 
diff --git a/network/mhfpacket/msg_mhf_operate_warehouse.go b/network/mhfpacket/msg_mhf_operate_warehouse.go
index df9222742..db198a3e7 100644
--- a/network/mhfpacket/msg_mhf_operate_warehouse.go
+++ b/network/mhfpacket/msg_mhf_operate_warehouse.go
@@ -32,7 +32,7 @@ func (m *MsgMhfOperateWarehouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.C
 	lenName := bf.ReadUint8()
 	bf.ReadUint16() // Zeroed
 	if lenName > 0 {
-		m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+		m.Name = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	}
 	return nil
 }
diff --git a/network/mhfpacket/msg_mhf_send_mail.go b/network/mhfpacket/msg_mhf_send_mail.go
index e79384b6b..bd3d1a345 100644
--- a/network/mhfpacket/msg_mhf_send_mail.go
+++ b/network/mhfpacket/msg_mhf_send_mail.go
@@ -35,8 +35,8 @@ func (m *MsgMhfSendMail) Parse(bf *byteframe.ByteFrame, ctx *clientctx.ClientCon
 	bf.ReadUint16() // Zeroed
 	m.Quantity = bf.ReadUint16()
 	m.ItemID = bf.ReadUint16()
-	m.Subject, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
-	m.Body, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Subject = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
+	m.Body = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	return nil
 }
 
diff --git a/network/mhfpacket/msg_mhf_update_guild_message_board.go b/network/mhfpacket/msg_mhf_update_guild_message_board.go
index fb1913aef..d37862068 100644
--- a/network/mhfpacket/msg_mhf_update_guild_message_board.go
+++ b/network/mhfpacket/msg_mhf_update_guild_message_board.go
@@ -38,8 +38,8 @@ func (m *MsgMhfUpdateGuildMessageBoard) Parse(bf *byteframe.ByteFrame, ctx *clie
 		m.StampID = bf.ReadUint32()
 		m.TitleLength = bf.ReadUint32()
 		m.BodyLength = bf.ReadUint32()
-		m.Title, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.TitleLength)))
-		m.Body, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.BodyLength)))
+		m.Title = stringsupport.SJISToUTF8Lossy(bf.ReadBytes(uint(m.TitleLength)))
+		m.Body = stringsupport.SJISToUTF8Lossy(bf.ReadBytes(uint(m.BodyLength)))
 	case 1:
 		m.PostID = bf.ReadUint32()
 	case 2:
@@ -47,8 +47,8 @@ func (m *MsgMhfUpdateGuildMessageBoard) Parse(bf *byteframe.ByteFrame, ctx *clie
 		bf.ReadBytes(8)
 		m.TitleLength = bf.ReadUint32()
 		m.BodyLength = bf.ReadUint32()
-		m.Title, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.TitleLength)))
-		m.Body, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.BodyLength)))
+		m.Title = stringsupport.SJISToUTF8Lossy(bf.ReadBytes(uint(m.TitleLength)))
+		m.Body = stringsupport.SJISToUTF8Lossy(bf.ReadBytes(uint(m.BodyLength)))
 	case 3:
 		m.PostID = bf.ReadUint32()
 		bf.ReadBytes(8)
diff --git a/network/mhfpacket/msg_mhf_update_house.go b/network/mhfpacket/msg_mhf_update_house.go
index c70e4633d..872ff3e6c 100644
--- a/network/mhfpacket/msg_mhf_update_house.go
+++ b/network/mhfpacket/msg_mhf_update_house.go
@@ -30,7 +30,7 @@ func (m *MsgMhfUpdateHouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Client
 	bf.ReadUint8() // Zeroed
 	bf.ReadUint8() // Zeroed
 	bf.ReadUint8() // Password length
-	m.Password, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Password = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	return nil
 }
 
diff --git a/server/channelserver/handlers_data.go b/server/channelserver/handlers_data.go
index bd7e228a0..d90ac040f 100644
--- a/server/channelserver/handlers_data.go
+++ b/server/channelserver/handlers_data.go
@@ -194,7 +194,7 @@ func handleMsgMhfLoaddata(s *Session, p mhfpacket.MHFPacket) {
 	_, _ = bf.Seek(88, io.SeekStart)
 	name := bf.ReadNullTerminatedBytes()
 	s.server.userBinary.Set(s.charID, 1, append(name, []byte{0x00}...))
-	s.Name, _ = stringsupport.SJISToUTF8(name)
+	s.Name = stringsupport.SJISToUTF8Lossy(name)
 }
 
 func handleMsgMhfSaveScenarioData(s *Session, p mhfpacket.MHFPacket) {
diff --git a/server/channelserver/handlers_guild_info.go b/server/channelserver/handlers_guild_info.go
index 351b72035..01d5ef424 100644
--- a/server/channelserver/handlers_guild_info.go
+++ b/server/channelserver/handlers_guild_info.go
@@ -287,14 +287,14 @@ func handleMsgMhfEnumerateGuild(s *Session, p mhfpacket.MHFPacket) {
 		if err == nil {
 			switch pkt.Type {
 			case mhfpacket.ENUMERATE_GUILD_TYPE_GUILD_NAME:
-				searchName, _ := stringsupport.SJISToUTF8(pkt.Data2.ReadNullTerminatedBytes())
+				searchName := stringsupport.SJISToUTF8Lossy(pkt.Data2.ReadNullTerminatedBytes())
 				for _, guild := range tempGuilds {
 					if strings.Contains(guild.Name, searchName) {
 						guilds = append(guilds, guild)
 					}
 				}
 			case mhfpacket.ENUMERATE_GUILD_TYPE_LEADER_NAME:
-				searchName, _ := stringsupport.SJISToUTF8(pkt.Data2.ReadNullTerminatedBytes())
+				searchName := stringsupport.SJISToUTF8Lossy(pkt.Data2.ReadNullTerminatedBytes())
 				for _, guild := range tempGuilds {
 					if strings.Contains(guild.LeaderName, searchName) {
 						guilds = append(guilds, guild)
@@ -364,14 +364,14 @@ func handleMsgMhfEnumerateGuild(s *Session, p mhfpacket.MHFPacket) {
 		tempAlliances, err = s.server.guildRepo.ListAlliances()
 		switch pkt.Type {
 		case mhfpacket.ENUMERATE_ALLIANCE_TYPE_ALLIANCE_NAME:
-			searchName, _ := stringsupport.SJISToUTF8(pkt.Data2.ReadNullTerminatedBytes())
+			searchName := stringsupport.SJISToUTF8Lossy(pkt.Data2.ReadNullTerminatedBytes())
 			for _, alliance := range tempAlliances {
 				if strings.Contains(alliance.Name, searchName) {
 					alliances = append(alliances, alliance)
 				}
 			}
 		case mhfpacket.ENUMERATE_ALLIANCE_TYPE_LEADER_NAME:
-			searchName, _ := stringsupport.SJISToUTF8(pkt.Data2.ReadNullTerminatedBytes())
+			searchName := stringsupport.SJISToUTF8Lossy(pkt.Data2.ReadNullTerminatedBytes())
 			for _, alliance := range tempAlliances {
 				if strings.Contains(alliance.ParentGuild.LeaderName, searchName) {
 					alliances = append(alliances, alliance)
diff --git a/server/channelserver/handlers_guild_ops.go b/server/channelserver/handlers_guild_ops.go
index 79011acc6..8a76b7225 100644
--- a/server/channelserver/handlers_guild_ops.go
+++ b/server/channelserver/handlers_guild_ops.go
@@ -108,7 +108,7 @@ func handleMsgMhfOperateGuild(s *Session, p mhfpacket.MHFPacket) {
 			doAckSimpleFail(s, pkt.AckHandle, make([]byte, 4))
 			return
 		}
-		guild.Comment, _ = stringsupport.SJISToUTF8(pkt.Data2.ReadNullTerminatedBytes())
+		guild.Comment = stringsupport.SJISToUTF8Lossy(pkt.Data2.ReadNullTerminatedBytes())
 		if err := s.server.guildRepo.Save(guild); err != nil {
 			s.logger.Error("Failed to save guild comment", zap.Error(err))
 		}
@@ -168,7 +168,7 @@ func handleMsgMhfOperateGuild(s *Session, p mhfpacket.MHFPacket) {
 }
 
 func handleRenamePugi(s *Session, bf *byteframe.ByteFrame, guild *Guild, num int) {
-	name, _ := stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	name := stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	switch num {
 	case 1:
 		guild.PugiName1 = name
diff --git a/server/channelserver/handlers_session.go b/server/channelserver/handlers_session.go
index 0362b0274..3919a244f 100644
--- a/server/channelserver/handlers_session.go
+++ b/server/channelserver/handlers_session.go
@@ -489,7 +489,7 @@ func handleMsgMhfTransitMessage(s *Session, p mhfpacket.MHFPacket) {
 		bf.ReadUint16() // term length
 		maxResults = bf.ReadUint16()
 		bf.ReadUint8() // Unk
-		term, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+		term = stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	case 3:
 		_ip := bf.ReadBytes(4)
 		ip = fmt.Sprintf("%d.%d.%d.%d", _ip[3], _ip[2], _ip[1], _ip[0])
diff --git a/server/channelserver/model_character.go b/server/channelserver/model_character.go
index e63228bb9..047744425 100644
--- a/server/channelserver/model_character.go
+++ b/server/channelserver/model_character.go
@@ -172,7 +172,7 @@ const (
 )
 
 func (save *CharacterSaveData) updateStructWithSaveData() {
-	save.Name, _ = stringsupport.SJISToUTF8(bfutil.UpToNull(save.decompSave[saveFieldNameOffset : saveFieldNameOffset+saveFieldNameLen]))
+	save.Name = stringsupport.SJISToUTF8Lossy(bfutil.UpToNull(save.decompSave[saveFieldNameOffset : saveFieldNameOffset+saveFieldNameLen]))
 	if save.decompSave[save.Pointers[pGender]] == 1 {
 		save.Gender = true
 	} else {
diff --git a/server/signserver/session.go b/server/signserver/session.go
index 4564f2f6c..bdbcf9a07 100644
--- a/server/signserver/session.go
+++ b/server/signserver/session.go
@@ -155,7 +155,7 @@ func (s *Session) handlePSSGN(bf *byteframe.ByteFrame) {
 
 func (s *Session) handlePSNLink(bf *byteframe.ByteFrame) {
 	_ = bf.ReadNullTerminatedBytes() // Client ID
-	credStr, _ := stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	credStr := stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	credentials := strings.Split(credStr, "\n")
 	tok := string(bf.ReadNullTerminatedBytes())
 	uid, resp := s.server.validateLogin(credentials[0], credentials[1])
@@ -195,8 +195,8 @@ func (s *Session) handlePSNLink(bf *byteframe.ByteFrame) {
 }
 
 func (s *Session) handleDSGN(bf *byteframe.ByteFrame) {
-	user, _ := stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
-	pass, _ := stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	user := stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
+	pass := stringsupport.SJISToUTF8Lossy(bf.ReadNullTerminatedBytes())
 	_ = string(bf.ReadNullTerminatedBytes()) // Unk
 	s.authenticate(user, pass)
 }