diff --git a/Source/Client/Session.cpp b/Source/Client/Session.cpp
index f17317fd..b199197b 100644
--- a/Source/Client/Session.cpp
+++ b/Source/Client/Session.cpp
@@ -1244,6 +1244,19 @@ bool CSession::IsGuildMemberName(const char* name) const {
   return std::strcmp(g_guildName.c_str(), name) == 0;
 }
 
+// OFFSET: 0x00DFA160
+// FUNCTION: fn_23571
+bool CSession::IsUnknownName5248(const char* name) const {
+  std::string value(name);
+  const std::size_t position = value.rfind("@");
+  if (position != std::string::npos && position >= 4) {
+    value.erase(position - 4, 3);
+  }
+
+  return std::binary_search(this->unknown_5248.begin(), this->unknown_5248.end(), value.c_str(),
+                            [](const char* left, const char* right) { return std::strcmp(left, right) < 0; });
+}
+
 // OFFSET: 0x00DDB580
 // FUNCTION: fn_23354
 void CSession::RemovePartyMemberByName(const char* name) {
diff --git a/Source/Client/Session.h b/Source/Client/Session.h
index 927fb78b..ca31b8df 100644
--- a/Source/Client/Session.h
+++ b/Source/Client/Session.h
@@ -250,7 +250,8 @@ public:
   /* 5218 */ std::vector<std::pair<const char*, int>> m_commandIds;
   /* 5224 */ std::vector<std::pair<const char*, const char*>> m_bgmFileNames;
   /* 5230 */ std::vector<std::pair<std::string, std::vector<std::string>>> m_fogParameters;
-  /* 523C */ unsigned char unknown_523C[0x18];
+  /* 523C */ unsigned char unknown_523C[0x0C];
+  /* 5248 */ std::vector<const char*> unknown_5248;
   /* 5254 */ std::map<int, float> m_npcLocationRadius;
   /* 525C */ unsigned char unknown_525C[0x38];
   /* 5294 */ const char* const* m_bodyJobNames;
@@ -605,6 +606,7 @@ public:
   bool IsGuildMemberCharacter(std::uint32_t characterId) const;
   bool IsGuildMemberCharacter(int characterId, char* name) const;
   bool IsGuildMemberName(const char* name) const;
+  bool IsUnknownName5248(const char* name) const;
   long long GetItem1760Total() const;
   ITEM_INFO GetItem1748At(int index) const;
   bool HasItem1718(std::uint32_t id) const;