diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj
index 02efc896..4e5a8f4d 100644
--- a/ArcFormats/ArcFormats.csproj
+++ b/ArcFormats/ArcFormats.csproj
@@ -979,6 +979,7 @@
     <Compile Include="Liar\ArcXFL.cs" />
     <Compile Include="KiriKiri\ArcXP3.cs" />
     <Compile Include="YuRis\ArcYPF.cs" />
+    <Compile Include="MOONSTONE\ArcPAK.cs" />
     <Compile Include="Macromedia\AudioEDIM.cs" />
     <Compile Include="Crowd\AudioEOG.cs" />
     <Compile Include="Entis\AudioMIO.cs" />
diff --git a/ArcFormats/MOONSTONE/ArcPAK.cs b/ArcFormats/MOONSTONE/ArcPAK.cs
new file mode 100644
index 00000000..dc75a724
--- /dev/null
+++ b/ArcFormats/MOONSTONE/ArcPAK.cs
@@ -0,0 +1,69 @@
+//! \file       ArcPAK.cs
+//! \date       2025 May 03
+//! \brief      MOONSTONE PAK resource archive.
+//
+// Copyright (C) 2015-2018 by morkt
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+//
+
+using System.Collections.Generic;
+using System.ComponentModel.Composition;
+using GameRes.Utility;
+
+namespace GameRes.Formats.Moonstone
+{
+    [Export(typeof(ArchiveFormat))]
+    public class MtsPakOpener : ArchiveFormat
+    {
+        public override string         Tag { get { return "PAK/DATATOP"; } }
+        public override string Description { get { return "MOONSTONE resource archive"; } }
+        public override uint     Signature { get { return 0x41544144; } } // 'DATA$TOP'
+        public override bool  IsHierarchic { get { return true; } }
+        public override bool      CanWrite { get { return false; } }
+
+        public override ArcFile TryOpen (ArcView file)
+        {
+            if (!file.View.AsciiEqual (4, "$TOP"))
+                return null;
+            int count = file.View.ReadInt32 (0x38) - 1;
+            if (!IsSaneCount (count))
+                return null;
+
+            uint index_offset = 0x40;
+            long base_offset = index_offset * (count + 1);
+            var name_buf = new byte[0x30];
+            var dir = new List<Entry> (count);
+            for (int i = 0; i < count; ++i)
+            {
+                file.View.Read (index_offset, name_buf, 0, 0x30);
+                var name = Binary.GetCString (name_buf, 0);
+                var entry = Create<Entry> (name);
+                entry.Size  = file.View.ReadUInt32 (index_offset + 0x38);
+                entry.Offset = base_offset + file.View.ReadUInt32 (index_offset + 0x34);
+                // accually there are 2 duplicate offsets for each file in the index 
+                if (!entry.CheckPlacement (file.MaxOffset))
+                    return null;
+                dir.Add (entry);
+                index_offset += 0x40;
+            }
+            return new ArcFile (file, this, dir);
+        }
+    }
+}