diff --git a/Source/Utility/NFileLog.cpp b/Source/Utility/NFileLog.cpp
new file mode 100644
index 0000000..c9b1c82
--- /dev/null
+++ b/Source/Utility/NFileLog.cpp
@@ -0,0 +1,82 @@
+#include "Utility/NFileLog.h"
+#include "Utility/Text/FormatString.h"
+
+#include <cstdio>
+#include <cstring>
+#include <ctime>
+#include <io.h>
+
+// FUNCTION: fn_07589
+bool NFileLog::Initialize(const char* directoryName, const char* filePrefix) {
+  char currentDirectory[1024]{};
+  GetCurrentDirectoryA(sizeof(currentDirectory), currentDirectory);
+  StringFormat(this->directory, sizeof(this->directory), static_cast<std::size_t>(-1), "%s\\%s", currentDirectory, directoryName);
+  CreateDirectoryA(this->directory, nullptr);
+  SYSTEMTIME currentTime;
+  GetLocalTime(&currentTime);
+  StringFormat(this->prefix, sizeof(this->prefix), static_cast<std::size_t>(-1), "%s", filePrefix);
+  this->year = currentTime.wYear;
+  this->month = currentTime.wMonth;
+  this->day = currentTime.wDay;
+
+  __time32_t cutoffTime = _time32(nullptr) - 15552000;
+  const std::tm cutoff = *_localtime32(&cutoffTime);
+  char cutoffPrefix[260]{};
+  StringFormat(cutoffPrefix, sizeof(cutoffPrefix), static_cast<std::size_t>(-1), "%s(%04d%02d%2d)", this->prefix, cutoff.tm_year + 1900, cutoff.tm_mon, cutoff.tm_mday);
+  char filename[1024]{};
+  StringFormat(filename, sizeof(filename), static_cast<std::size_t>(-1), "%s\\%s*.*", this->directory, this->prefix);
+  WIN32_FIND_DATAA found{};
+  HANDLE search = FindFirstFileA(filename, &found);
+  if (search != INVALID_HANDLE_VALUE) {
+    do {
+      if (std::strncmp(found.cFileName, cutoffPrefix, std::strlen(cutoffPrefix)) < 0) {
+        char expired[260]{};
+        StringFormat(expired, sizeof(expired), static_cast<std::size_t>(-1), "%s\\%s", this->directory, found.cFileName);
+        _unlink(expired);
+      }
+    } while (FindNextFileA(search, &found));
+    FindClose(search);
+  }
+
+  int lastExisting = -1;
+  int nextIndex = 0;
+  for (;; ++nextIndex) {
+    char candidate[1024]{};
+    char base[1024]{};
+    StringFormat(base, sizeof(base), static_cast<std::size_t>(-1), "%s\\%s(%04d%02d%02d)", this->directory, this->prefix, this->year, this->month, this->day);
+    if (nextIndex != 0) {
+      StringFormat(candidate, sizeof(candidate), static_cast<std::size_t>(-1), "%s-%04d.txt", base, nextIndex);
+    } else {
+      StringFormat(candidate, sizeof(candidate), static_cast<std::size_t>(-1), "%s.txt", base);
+    }
+    if (_access(candidate, 0) != 0) {
+      break;
+    }
+    lastExisting = nextIndex;
+  }
+
+  bool reuse = false;
+  if (lastExisting >= 0) {
+    std::memset(filename, 0, sizeof(filename));
+    char base[1024]{};
+    StringFormat(base, sizeof(base), static_cast<std::size_t>(-1), "%s\\%s(%04d%02d%02d)", this->directory, this->prefix, this->year, this->month, this->day);
+    if (lastExisting != 0) {
+      StringFormat(filename, sizeof(filename), static_cast<std::size_t>(-1), "%s-%04d.txt", base, lastExisting);
+    } else {
+      StringFormat(filename, sizeof(filename), static_cast<std::size_t>(-1), "%s.txt", base);
+    }
+    FILE* file = nullptr;
+    if (fopen_s(&file, filename, "r") == 0 && file != nullptr) {
+      std::fseek(file, 0, SEEK_END);
+      this->fileSize = std::ftell(file);
+      std::fclose(file);
+      reuse = this->fileSize < 3145728;
+    }
+  }
+  if (!reuse) {
+    this->fileSize = 0;
+    lastExisting = nextIndex;
+  }
+  this->fileIndex = lastExisting;
+  return static_cast<unsigned>(lastExisting) <= 9999;
+}
diff --git a/Source/Utility/NFileLog.h b/Source/Utility/NFileLog.h
new file mode 100644
index 0000000..77c1648
--- /dev/null
+++ b/Source/Utility/NFileLog.h
@@ -0,0 +1,31 @@
+#ifndef RAGNAROK_SOURCE_UTILITY_NFILELOG_H
+#define RAGNAROK_SOURCE_UTILITY_NFILELOG_H
+
+#include <cstdint>
+#include <windows.h>
+
+class NFileLog {
+public:
+  // INLINED
+  virtual ~NFileLog() {
+    DeleteCriticalSection(&this->criticalSection);
+  }
+
+  bool Initialize(const char* directoryName, const char* prefix);
+
+  /* 0004 */ std::uint32_t unknown_0004;
+  /* 0008 */ CRITICAL_SECTION criticalSection;
+  /* 0020 */ char directory[1024];
+  /* 0420 */ char prefix[1024];
+  /* 0820 */ int year;
+  /* 0824 */ int month;
+  /* 0828 */ int day;
+  /* 082C */ int fileIndex;
+  /* 0830 */ int fileSize;
+};
+
+#if defined(_WIN32) && !defined(_WIN64)
+static_assert(sizeof(NFileLog) == 0x834);
+#endif
+
+#endif
diff --git a/compile.json b/compile.json
index e4fb121..806e6bd 100644
--- a/compile.json
+++ b/compile.json
@@ -601,6 +601,7 @@
   "Source/Utility/Math/ClientAngles.cpp": 0,
   "Source/Utility/Math/RadialGrid.cpp": 0,
   "Source/Utility/Math/RayTriangle.cpp": 0,
+  "Source/Utility/NFileLog.cpp": 0,
   "Source/Utility/NIPAddr.cpp": 0,
   "Source/Utility/ProcessSecurity.cpp": 0,
   "Source/Utility/Text/Base64.cpp": 0,