diff --git a/build/CodeGen/results.csv b/build/CodeGen/results.csv
index 520d2e68..f6eeebe6 100644
--- a/build/CodeGen/results.csv
+++ b/build/CodeGen/results.csv
@@ -1069,6 +1069,7 @@ Module,DescriptionStart,DescriptionEnd,Flags,Namespace,Name,Summary
 2,6396,,,,UnsupportedRollbackOnlyModifiedForDirectorySaveDataFileSystem,
 2,6397,,,,UnsupportedOperateRangeForRegionSwitchStorage,
 2,6398,,,,UnsupportedOperateRangeForSaveDataFile,
+2,6399,,,,UnsupportedOperateRangeForApplicationTemporaryFile,
 
 2,6400,6449,,,PermissionDenied,
 2,6403,,,,HostFileSystemOperationDisabled,Returned when opening a host FS on a retail device.
diff --git a/src/LibHac/Fs/ResultFs.cs b/src/LibHac/Fs/ResultFs.cs
index ad9fb24f..b6b9cdc5 100644
--- a/src/LibHac/Fs/ResultFs.cs
+++ b/src/LibHac/Fs/ResultFs.cs
@@ -1962,6 +1962,8 @@ public static class ResultFs
                 public static Result.Base UnsupportedOperateRangeForRegionSwitchStorage => new Result.Base(ModuleFs, 6397);
                 /// <summary>Error code: 2002-6398; Inner value: 0x31fc02</summary>
                 public static Result.Base UnsupportedOperateRangeForSaveDataFile => new Result.Base(ModuleFs, 6398);
+                /// <summary>Error code: 2002-6399; Inner value: 0x31fe02</summary>
+                public static Result.Base UnsupportedOperateRangeForApplicationTemporaryFile => new Result.Base(ModuleFs, 6399);
 
             /// <summary>Error code: 2002-6400; Range: 6400-6449; Inner value: 0x320002</summary>
             public static Result.Base PermissionDenied { [MethodImpl(MethodImplOptions.AggressiveInlining)] get => new Result.Base(ModuleFs, 6400, 6449); }
diff --git a/src/LibHac/FsSystem/ApplicationTemporaryFileSystem.cs b/src/LibHac/FsSystem/ApplicationTemporaryFileSystem.cs
index 0629c0f1..a3a61a29 100644
--- a/src/LibHac/FsSystem/ApplicationTemporaryFileSystem.cs
+++ b/src/LibHac/FsSystem/ApplicationTemporaryFileSystem.cs
@@ -1,7 +1,9 @@
 // ReSharper disable UnusedMember.Local UnusedType.Local
 #pragma warning disable CS0169 // Field is never used
 using System;
+using System.Runtime.CompilerServices;
 using LibHac.Common;
+using LibHac.Diag;
 using LibHac.Fs;
 using LibHac.Fs.Fsa;
 using LibHac.FsSystem.Save;
@@ -14,43 +16,75 @@ file class ApplicationTemporaryFile : IFile
 
     public ApplicationTemporaryFile(ref UniqueRef<IFile> file)
     {
-        throw new NotImplementedException();
+        _file = new UniqueRef<IFile>(ref file);
+
+        Assert.SdkRequiresNotNull(in _file);
     }
 
     public override void Dispose()
     {
-        throw new NotImplementedException();
+        Assert.SdkRequiresNotNull(in _file);
+
+        _file.Destroy();
+        base.Dispose();
     }
 
     protected override Result DoRead(out long bytesRead, long offset, Span<byte> destination, in ReadOption option)
     {
-        throw new NotImplementedException();
+        Assert.SdkRequiresNotNull(in _file);
+
+        Result res = _file.Get.Read(out bytesRead, offset, destination);
+
+        if (res.IsFailure())
+        {
+            if (ResultFs.InvalidSaveDataFileReadOffset.Includes(res))
+            {
+                return ResultFs.OutOfRange.LogConverted(res);
+            }
+
+            return res.Miss();
+        }
+
+        return Result.Success;
     }
 
     protected override Result DoWrite(long offset, ReadOnlySpan<byte> source, in WriteOption option)
     {
-        throw new NotImplementedException();
+        Assert.SdkRequiresNotNull(in _file);
+
+        return _file.Get.Write(offset, source, in option).Ret();
     }
 
     protected override Result DoFlush()
     {
-        throw new NotImplementedException();
+        Assert.SdkRequiresNotNull(in _file);
+
+        return _file.Get.Flush().Ret();
     }
 
     protected override Result DoSetSize(long size)
     {
-        throw new NotImplementedException();
+        Assert.SdkRequiresNotNull(in _file);
+
+        return _file.Get.SetSize(size).Ret();
     }
 
     protected override Result DoGetSize(out long size)
     {
-        throw new NotImplementedException();
+        Assert.SdkRequiresNotNull(in _file);
+
+        return _file.Get.GetSize(out size).Ret();
     }
 
     protected override Result DoOperateRange(Span<byte> outBuffer, OperationId operationId, long offset, long size,
         ReadOnlySpan<byte> inBuffer)
     {
-        throw new NotImplementedException();
+        Assert.SdkRequiresNotNull(in _file);
+
+        if (operationId == OperationId.InvalidateCache)
+            return ResultFs.UnsupportedOperateRangeForApplicationTemporaryFile.Log();
+
+        return _file.Get.OperateRange(outBuffer, operationId, offset, size, inBuffer).Ret();
     }
 }
 
@@ -65,140 +99,177 @@ public class ApplicationTemporaryFileSystem : ISaveDataFileSystem, ISaveDataExtr
 
     public ApplicationTemporaryFileSystem()
     {
-        throw new NotImplementedException();
+        _baseStorage = new SharedRef<IStorage>();
+        _saveFsDriver = new IntegritySaveDataFileSystemDriver();
+        _isInitialized = false;
+        _cacheObserver = null;
     }
 
     public override void Dispose()
     {
-        throw new NotImplementedException();
+        if (_isInitialized)
+        {
+            _saveFsDriver.Commit().IgnoreResult();
+            _saveFsDriver.FinalizeObject();
+            _cacheObserver?.Unregister(_spaceId, _saveDataId);
+
+            _isInitialized = false;
+        }
+
+        _saveFsDriver.Dispose();
+        _baseStorage.Destroy();
+        base.Dispose();
     }
 
     public Result Initialize(IStorage baseStorage, IBufferManager bufferManager, IMacGenerator macGenerator,
         IHash256GeneratorFactorySelector hashGeneratorFactorySelector)
     {
-        throw new NotImplementedException();
+        Result res = baseStorage.GetSize(out long size);
+        if (res.IsFailure()) return res.Miss();
+
+        using var baseSubStorage = new ValueSubStorage(baseStorage, 0, size);
+        res = _saveFsDriver.Initialize(in baseSubStorage, bufferManager, macGenerator, hashGeneratorFactorySelector);
+        if (res.IsFailure()) return res.Miss();
+
+        _isInitialized = true;
+
+        return Result.Success;
     }
 
     public Result Initialize(ref readonly SharedRef<IStorage> baseStorage, IBufferManager bufferManager,
         IMacGenerator macGenerator, IHash256GeneratorFactorySelector hashGeneratorFactorySelector)
     {
-        throw new NotImplementedException();
+        _baseStorage.SetByCopy(in baseStorage);
+
+        return Initialize(_baseStorage.Get, bufferManager, macGenerator, hashGeneratorFactorySelector).Ret();
     }
 
     protected override Result DoCreateFile(ref readonly Path path, long size, CreateFileOptions option)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.CreateFile(in path, size, option).Ret();
     }
 
     protected override Result DoDeleteFile(ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.DeleteFile(in path).Ret();
     }
 
     protected override Result DoCreateDirectory(ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.CreateDirectory(in path).Ret();
     }
 
     protected override Result DoDeleteDirectory(ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.DeleteDirectory(in path).Ret();
     }
 
     protected override Result DoDeleteDirectoryRecursively(ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.DeleteDirectoryRecursively(in path).Ret();
     }
 
     protected override Result DoCleanDirectoryRecursively(ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.CleanDirectoryRecursively(in path).Ret();
     }
 
     protected override Result DoRenameFile(ref readonly Path currentPath, ref readonly Path newPath)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.RenameFile(in currentPath, in newPath).Ret();
     }
 
     protected override Result DoRenameDirectory(ref readonly Path currentPath, ref readonly Path newPath)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.RenameDirectory(in currentPath, in newPath).Ret();
     }
 
     protected override Result DoGetEntryType(out DirectoryEntryType entryType, ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.GetEntryType(out entryType, in path).Ret();
     }
 
     protected override Result DoOpenFile(ref UniqueRef<IFile> outFile, ref readonly Path path, OpenMode mode)
     {
-        throw new NotImplementedException();
+        using var file = new UniqueRef<IFile>();
+        Result res = _saveFsDriver.OpenFile(ref file.Ref, in path, mode);
+        if (res.IsFailure()) return res.Miss();
+
+        using var wrapperFile = new UniqueRef<ApplicationTemporaryFile>(new ApplicationTemporaryFile(ref file.Ref));
+
+        outFile.Set(ref wrapperFile.Ref);
+        return Result.Success;
     }
 
     protected override Result DoOpenDirectory(ref UniqueRef<IDirectory> outDirectory, ref readonly Path path,
         OpenDirectoryMode mode)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.OpenDirectory(ref outDirectory, in path, mode).Ret();
     }
 
     protected override Result DoCommit()
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.Commit().Ret();
     }
 
     protected override Result DoCommitProvisionally(long counter)
     {
-        throw new NotImplementedException();
+        return ResultFs.UnsupportedCommitProvisionallyForApplicationTemporaryFileSystem.Log();
     }
 
     protected override Result DoRollback()
     {
-        throw new NotImplementedException();
+        return Result.Success;
     }
 
     protected override Result DoGetFreeSpaceSize(out long freeSpace, ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.GetFreeSpaceSize(out freeSpace, in path).Ret();
     }
 
     protected override Result DoGetTotalSpaceSize(out long totalSpace, ref readonly Path path)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.GetTotalSpaceSize(out totalSpace, in path).Ret();
     }
 
     public override bool IsSaveDataFileSystemCacheEnabled()
     {
-        throw new NotImplementedException();
+        return false;
     }
 
     public override Result RollbackOnlyModified()
     {
-        throw new NotImplementedException();
+        return ResultFs.UnsupportedRollbackOnlyModifiedForApplicationTemporaryFileSystem.Log();
     }
 
     protected override Result DoGetFileSystemAttribute(out FileSystemAttribute outAttribute)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.GetFileSystemAttribute(out outAttribute).Ret();
     }
 
     public override Result WriteExtraData(in SaveDataExtraData extraData)
     {
-        throw new NotImplementedException();
+        return _saveFsDriver.WriteExtraData(in Unsafe.As<SaveDataExtraData, IntegritySaveDataFileSystem.ExtraData>(ref Unsafe.AsRef(in extraData))).Ret();
     }
 
     public override Result CommitExtraData(bool updateTimeStamp)
     {
-        throw new NotImplementedException();
+        return DoCommit().Ret();
     }
 
     public override Result ReadExtraData(out SaveDataExtraData extraData)
     {
-        throw new NotImplementedException();
+        UnsafeHelpers.SkipParamInit(out extraData);
+        _saveFsDriver.ReadExtraData(out Unsafe.As<SaveDataExtraData, IntegritySaveDataFileSystem.ExtraData>(ref extraData));
+
+        return Result.Success;
     }
 
     public override void RegisterExtraDataAccessorObserver(ISaveDataExtraDataAccessorObserver observer, SaveDataSpaceId spaceId,
         ulong saveDataId)
     {
-        throw new NotImplementedException();
+        _cacheObserver = observer;
+        _spaceId = spaceId;
+        _saveDataId = saveDataId;
     }
 }
\ No newline at end of file
diff --git a/src/LibHac/FsSystem/Save/IntegritySaveDataFileSystemDriver.cs b/src/LibHac/FsSystem/Save/IntegritySaveDataFileSystemDriver.cs
index 751443df..9b257ce3 100644
--- a/src/LibHac/FsSystem/Save/IntegritySaveDataFileSystemDriver.cs
+++ b/src/LibHac/FsSystem/Save/IntegritySaveDataFileSystemDriver.cs
@@ -66,7 +66,7 @@ public class IntegritySaveDataFileSystemDriver : ProxyFileSystemWithRetryingBuff
         throw new NotImplementedException();
     }
 
-    public void WriteExtraData(in IntegritySaveDataFileSystem.ExtraData extraData)
+    public Result WriteExtraData(in IntegritySaveDataFileSystem.ExtraData extraData)
     {
         throw new NotImplementedException();
     }