diff --git a/src/LibHac/Common/FixedArrays/Array20.cs b/src/LibHac/Common/FixedArrays/Array20.cs
new file mode 100644
index 00000000..5edeba12
--- /dev/null
+++ b/src/LibHac/Common/FixedArrays/Array20.cs
@@ -0,0 +1,31 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace LibHac.Common.FixedArrays;
+
+[StructLayout(LayoutKind.Sequential)]
+public struct Array20<T>
+{
+    public const int Length = 20;
+
+    private Array16<T> _0;
+    private Array4<T> _16;
+
+    public ref T this[int i] => ref Items[i];
+
+    public Span<T> Items
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => SpanHelpers.CreateSpan(ref MemoryMarshal.GetReference(_0.Items), Length);
+    }
+
+    public readonly ReadOnlySpan<T> ItemsRo
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => SpanHelpers.CreateSpan(ref MemoryMarshal.GetReference(_0.ItemsRo), Length);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static implicit operator ReadOnlySpan<T>(in Array20<T> value) => value.ItemsRo;
+}
\ No newline at end of file
diff --git a/src/LibHac/Common/FixedArrays/Array60.cs b/src/LibHac/Common/FixedArrays/Array60.cs
new file mode 100644
index 00000000..f7a04c95
--- /dev/null
+++ b/src/LibHac/Common/FixedArrays/Array60.cs
@@ -0,0 +1,32 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace LibHac.Common.FixedArrays;
+
+[StructLayout(LayoutKind.Sequential)]
+public struct Array60<T>
+{
+    public const int Length = 60;
+
+    private Array32<T> _0;
+    private Array16<T> _32;
+    private Array12<T> _48;
+
+    public ref T this[int i] => ref Items[i];
+
+    public Span<T> Items
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => SpanHelpers.CreateSpan(ref MemoryMarshal.GetReference(_0.Items), Length);
+    }
+
+    public readonly ReadOnlySpan<T> ItemsRo
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => SpanHelpers.CreateSpan(ref MemoryMarshal.GetReference(_0.ItemsRo), Length);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static implicit operator ReadOnlySpan<T>(in Array60<T> value) => value.ItemsRo;
+}
\ No newline at end of file
diff --git a/src/LibHac/Fs/Fsa/UserFile.cs b/src/LibHac/Fs/Fsa/UserFile.cs
index 60b6598e..89a6a630 100644
--- a/src/LibHac/Fs/Fsa/UserFile.cs
+++ b/src/LibHac/Fs/Fsa/UserFile.cs
@@ -7,6 +7,10 @@ using static LibHac.Fs.Impl.AccessLogStrings;
 
 namespace LibHac.Fs.Fsa;
 
+/// <summary>
+/// Contains functions for interacting with opened files.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 [SkipLocalsInit]
 public static class UserFile
 {
@@ -215,12 +219,75 @@ public static class UserFile
         return rc;
     }
 
-    public static Result InvalidateCache(this FileSystemClient fs, FileHandle handle, long offset, long size)
+    public static Result InvalidateCache(this FileSystemClient fs, FileHandle handle)
     {
-        Result rc = Get(handle).OperateRange(Span<byte>.Empty, OperationId.InvalidateCache, offset, size,
+        Result rc = Get(handle).OperateRange(Span<byte>.Empty, OperationId.InvalidateCache, 0, long.MaxValue,
             ReadOnlySpan<byte>.Empty);
 
         fs.Impl.AbortIfNeeded(rc);
         return rc;
     }
-}
+
+    public static Result QueryUnpreparedRange(this FileSystemClient fs, out Range unpreparedRange, FileHandle handle)
+    {
+        UnsafeHelpers.SkipParamInit(out unpreparedRange);
+        Unsafe.SkipInit(out UnpreparedRangeInfo info);
+
+        Result rc = Get(handle).OperateRange(SpanHelpers.AsByteSpan(ref info), OperationId.QueryUnpreparedRange, 0, 0,
+            ReadOnlySpan<byte>.Empty);
+
+        fs.Impl.AbortIfNeeded(rc);
+        if (rc.IsFailure()) return rc.Miss();
+
+        unpreparedRange = info.Range;
+        return Result.Success;
+    }
+
+    public static Result QueryUnpreparedRangeDetail(this FileSystemClient fs,
+        out UnpreparedRangeInfo unpreparedRangeInfo, FileHandle handle)
+    {
+        UnsafeHelpers.SkipParamInit(out unpreparedRangeInfo);
+        Unsafe.SkipInit(out UnpreparedRangeInfo info);
+
+        Result rc = Get(handle).OperateRange(SpanHelpers.AsByteSpan(ref info), OperationId.QueryUnpreparedRange, 0, 0,
+            ReadOnlySpan<byte>.Empty);
+
+        fs.Impl.AbortIfNeeded(rc);
+        if (rc.IsFailure()) return rc.Miss();
+
+        unpreparedRangeInfo = info;
+        return Result.Success;
+    }
+
+    public static Result QueryLazyLoadCompletionRate(this FileSystemClient fs, out int completionRate,
+        FileHandle handle, int guideIndex)
+    {
+        UnsafeHelpers.SkipParamInit(out completionRate);
+
+        Unsafe.SkipInit(out UnpreparedRangeInfo info);
+        var args = new LazyLoadArguments { GuideIndex = guideIndex };
+
+        Result rc = Get(handle).OperateRange(SpanHelpers.AsByteSpan(ref info), OperationId.QueryLazyLoadCompletionRate,
+            0, 0, SpanHelpers.AsReadOnlyByteSpan(in args));
+
+        fs.Impl.AbortIfNeeded(rc);
+        if (rc.IsFailure()) return rc.Miss();
+
+        completionRate = info.CompletionRate;
+        return Result.Success;
+    }
+
+    public static Result ReadyLazyLoadFileForciblyForDebug(this FileSystemClient fs, FileHandle handle, long offset,
+        long size)
+    {
+        Unsafe.SkipInit(out UnpreparedRangeInfo info);
+
+        Result rc = Get(handle).OperateRange(SpanHelpers.AsByteSpan(ref info), OperationId.ReadyLazyLoadFile,
+            offset, size, ReadOnlySpan<byte>.Empty);
+
+        fs.Impl.AbortIfNeeded(rc);
+        if (rc.IsFailure()) return rc.Miss();
+
+        return Result.Success;
+    }
+}
\ No newline at end of file
diff --git a/src/LibHac/Fs/LazyLoadTypes.cs b/src/LibHac/Fs/LazyLoadTypes.cs
new file mode 100644
index 00000000..f5b2f025
--- /dev/null
+++ b/src/LibHac/Fs/LazyLoadTypes.cs
@@ -0,0 +1,19 @@
+using LibHac.Common.FixedArrays;
+
+namespace LibHac.Fs;
+
+public struct UnpreparedRangeInfo
+{
+    public Range Range;
+    public long FileSize;
+    public long PreparedRangeSize;
+    public long TotalReadSize;
+    public int CompletionRate;
+    public Array20<byte> Reserved;
+}
+
+public struct LazyLoadArguments
+{
+    public int GuideIndex;
+    public Array60<byte> Reserved;
+}
\ No newline at end of file
diff --git a/tests/LibHac.Tests/Fs/LazyLoadTypeTests.cs b/tests/LibHac.Tests/Fs/LazyLoadTypeTests.cs
new file mode 100644
index 00000000..4cbf9562
--- /dev/null
+++ b/tests/LibHac.Tests/Fs/LazyLoadTypeTests.cs
@@ -0,0 +1,22 @@
+// ReSharper disable InconsistentNaming
+
+using System.Runtime.CompilerServices;
+using LibHac.Fs;
+using Xunit;
+
+namespace LibHac.Tests.Fs;
+
+public class LazyLoadTypeTests
+{
+    [Fact]
+    public static void UnpreparedRangeInfoSizeIs0x40()
+    {
+        Assert.Equal(0x40, Unsafe.SizeOf<UnpreparedRangeInfo>());
+    }
+
+    [Fact]
+    public static void LazyLoadArgumentsSizeIs0x40()
+    {
+        Assert.Equal(0x40, Unsafe.SizeOf<LazyLoadArguments>());
+    }
+}
\ No newline at end of file