diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj
index e5b88d69..44b528d9 100644
--- a/ArcFormats/ArcFormats.csproj
+++ b/ArcFormats/ArcFormats.csproj
@@ -134,6 +134,7 @@
     <Compile Include="AdvSys\ImageGWD.cs" />
     <Compile Include="Ail\ArcLNK2.cs" />
     <Compile Include="AIRNovel\ArcAIR.cs" />
+    <Compile Include="ArrayPoolGuard.cs" />
     <Compile Include="Artemis\ImageNekoPNG.cs" />
     <Compile Include="CsWare\AudioWAV.cs" />
     <Compile Include="CsWare\ImageGDT.cs" />
@@ -208,6 +209,7 @@
     <Compile Include="MAGES\ImageBIN.cs" />
     <Compile Include="Mugi\ArcBIN.cs" />
     <Compile Include="Musica\ArcPAK.cs" />
+    <Compile Include="NekoNyan\SpriteArcDAT.cs" />
     <Compile Include="NipponIchi\ArcCASN.cs" />
     <Compile Include="NipponIchi\ArcPSFS.cs" />
     <Compile Include="NipponIchi\ImageNMT.cs" />
@@ -1343,7 +1345,6 @@
     </EmbeddedResource>
     <EmbeddedResource Include="Strings\arcStrings.ru-RU.resx" />
   </ItemGroup>
-  <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <PropertyGroup>
     <PreBuildEvent>perl "$(SolutionDir)inc-revision.pl" "$(ProjectPath)" $(ConfigurationName)
diff --git a/ArcFormats/ArrayPoolGuard.cs b/ArcFormats/ArrayPoolGuard.cs
new file mode 100644
index 00000000..b9ae0086
--- /dev/null
+++ b/ArcFormats/ArrayPoolGuard.cs
@@ -0,0 +1,67 @@
+using System;
+using System.Buffers;
+using System.Threading;
+
+namespace GameRes.Utility
+{
+    internal struct ArrayPoolGuard<T> : IDisposable
+    {
+        private readonly ArrayPool<T> m_pool;
+        private T[] m_array;
+
+        public T[] Array
+        {
+            get
+            {
+                if (m_array == null)
+                    throw new ObjectDisposedException(nameof(ArrayPoolGuard<T>));
+                return m_array;
+            }
+        }
+
+        public ArrayPoolGuard(ArrayPool<T> pool, int minimumLength)
+        {
+            m_pool = pool;
+            m_array = pool.Rent(minimumLength);
+            if (m_array == null)
+                throw new InvalidOperationException("ArrayPool.Rent returned null");
+        }
+
+        public static implicit operator T[](ArrayPoolGuard<T> guard) => guard.Array;
+
+        public void Dispose()
+        {
+            var oldSavedArray = Interlocked.CompareExchange(ref m_array, null, m_array);
+            if (oldSavedArray == null) return;
+            m_pool.Return(oldSavedArray);
+            m_array = null;
+        }
+
+        #region Array Properties
+
+        public T this[int index]
+        {
+            get => Array[index];
+            set => Array[index] = value;
+        }
+
+        public int Length => Array.Length;
+
+        #endregion
+    }
+
+    internal static class ArrayPoolExtension
+    {
+        /// <summary>
+        /// Used in conjunction with the using statement to borrow arrays from the pool and automatically return it at the end of using
+        /// </summary>
+        /// <param name="pool">The array pool rent from</param>
+        /// <param name="min_length">The minimum size of the array</param>
+        /// <typeparam name="T">Array element type</typeparam>
+        /// <returns>An <see cref="ArrayPoolGuard{T}"/> struct，it will return the array to the pool when disposed being invoked</returns>
+        public static ArrayPoolGuard<T> RentSafe<T>(this ArrayPool<T> pool, int min_length)
+        {
+            return new ArrayPoolGuard<T>(pool, min_length);
+        }
+    }
+}
\ No newline at end of file
diff --git a/ArcFormats/NekoNyan/SpriteArcDAT.cs b/ArcFormats/NekoNyan/SpriteArcDAT.cs
new file mode 100644
index 00000000..6a58426a
--- /dev/null
+++ b/ArcFormats/NekoNyan/SpriteArcDAT.cs
@@ -0,0 +1,273 @@
+using System;
+using System.Buffers;
+using System.Collections.Generic;
+using System.ComponentModel.Composition;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using System.Text;
+
+using GameRes.Utility;
+
+namespace GameRes.Formats.NekoNyan
+{
+    public class SpriteArcEntry : PackedEntry
+    {
+        public SpriteDecryptParams DecryptParams { get; set; }
+        public uint Key                          { get; set; }
+    }
+
+    [Serializable]
+    public class SpriteScheme : ResourceScheme
+    {
+        public Dictionary<string, SpriteDecryptParams> KnownGame = new Dictionary<string, SpriteDecryptParams>();
+    }
+
+    [Serializable]
+    [SuppressMessage("ReSharper", "UnassignedField.Global")]
+    public class SpriteDecryptParams
+    {
+        public long FileCountBeginByte;
+        public uint GenKeyInitMul;
+        public uint GenKeyInitAdd;
+        public int GenKeyInitShift;
+        public uint GenKeyRoundAdd;
+        public uint GenKeyRoundAnd;
+        public int GenKeyRoundShift;
+
+        public long DecryMod1;
+        public byte DecryAdd;
+        public long DecryMod2;
+        public byte DecryXor;
+    }
+
+    [Export(typeof(ArchiveFormat))]
+    public class SpriteArcDat : ArchiveFormat
+    {
+        private SpriteScheme m_scheme = new SpriteScheme();
+        
+        public override string Tag         { get; } = "DAT/NEKONYAN/SPRITE";
+        public override string Description { get; } = "NEKONYAN/SPRITE resource archive";
+        public override uint Signature     { get; } = 0x00000000;
+        public override bool IsHierarchic  { get; } = true;
+
+        public override ResourceScheme Scheme
+        {
+            get => m_scheme;
+            set => m_scheme = (SpriteScheme)value;
+        }
+
+        public override ArcFile TryOpen(ArcView view)
+        {
+            const int header_size = 1024;
+            if (view.MaxOffset < header_size)
+                return null;  // file too small
+
+            if (!TryIdentifyGame(view, out var game))
+                return null;  // not a known game
+            
+            int file_count = 0;
+            for (long i = game.FileCountBeginByte; i < header_size - 4; i += 4)
+                file_count += view.View.ReadInt32(i);
+
+            if (file_count == 0)
+                return new ArcFile(view, this, Array.Empty<Entry>());
+            
+            var entries = new List<Entry>();
+            uint seed1 = view.View.ReadUInt32(0xD4);
+            uint seed2 = view.View.ReadUInt32(0x5C);
+
+            // table of contents is encrypted, need to decrypt it first
+            int toc_size = 16 * file_count;
+            if (toc_size > view.MaxOffset - header_size)
+                return null;  // file too small
+            
+            using (var toc_buffer = ArrayPool<byte>.Shared.RentSafe(toc_size))
+            {
+                if (view.View.Read(header_size, toc_buffer, 0, (uint)toc_size) != toc_size)
+                    return null;  // file too small
+                
+                SpriteDecryptionUtils.Decrypt(new Span<byte>(toc_buffer, 0, toc_size), seed1, game);
+
+                int content_offset = BitConverter.ToInt32(toc_buffer, 12);
+                int const_size = content_offset - (header_size + toc_size);
+
+                if (content_offset > view.MaxOffset)
+                    return null;  // file too small
+                
+                using (var const_buffer = ArrayPool<byte>.Shared.RentSafe(const_size))
+                {
+                    if (view.View.Read(header_size + toc_size, const_buffer, 0, (uint)const_size) != const_size)
+                        return null;  // file too small
+                    
+                    SpriteDecryptionUtils.Decrypt(new Span<byte>(const_buffer, 0, const_size), seed2, game);
+
+                    for (int i = 0; i < file_count; i++)
+                    {
+                        int entry_offset = 16 * i;
+                        uint size = BitConverter.ToUInt32(toc_buffer, entry_offset);
+                        int const_addr = BitConverter.ToInt32(toc_buffer, entry_offset + 4);
+                        uint key = BitConverter.ToUInt32(toc_buffer, entry_offset + 8);
+                        uint data_addr = BitConverter.ToUInt32(toc_buffer, entry_offset + 12);
+
+                        int cnt = 0;
+                        for (; const_addr + cnt < const_size && const_buffer[const_addr + cnt] != 0; cnt++) { }
+
+                        string name = Encoding.ASCII.GetString(const_buffer, const_addr, cnt);
+                        entries.Add(new SpriteArcEntry
+                        {
+                            DecryptParams = game,
+                            Name = name,
+                            Offset = data_addr,
+                            Size = size,
+                            Key = key,
+                            Type = FormatCatalog.Instance.GetTypeFromName(name)
+                        });
+                    }
+                }
+            }
+
+            return new ArcFile(view, this, entries);
+        }
+
+        public override Stream OpenEntry(ArcFile arc, Entry entry)
+        {
+            if (!(entry is SpriteArcEntry sprite_entry))
+                return arc.File.CreateStream (entry.Offset, entry.Size);
+            
+            return new SpriteDecryptionStream(arc.File.CreateStream(entry.Offset, entry.Size), sprite_entry.Key, sprite_entry.DecryptParams);
+        }
+
+        private bool TryIdentifyGame(ArcView view, out SpriteDecryptParams decrypt_params)
+        {
+            decrypt_params = null;
+            string info_path = VFS.CombinePath(VFS.GetDirectoryName(view.Name), "app.info");
+            if (!File.Exists(info_path))
+                return false;
+
+            using (var sr = new StreamReader(info_path, Encoding.UTF8))
+            {
+                string company = sr.ReadLine();
+                string product = sr.ReadLine();
+
+                if (string.IsNullOrEmpty(company) || string.IsNullOrEmpty(product))
+                    return false;
+
+                return m_scheme.KnownGame.TryGetValue($"{company}/{product}", out decrypt_params);
+            }
+        }
+    }
+    
+    public static class SpriteDecryptionUtils
+    {
+        public const int KeyTableSize = 256;
+        
+        public static void Decrypt(Span<byte> data, uint key, SpriteDecryptParams decry_params, long base_index = 0)
+        {
+            Span<byte> key_table = stackalloc byte[KeyTableSize];
+            GenerateKeyTable(key_table, key, decry_params);
+            Decrypt(data, key_table, decry_params, base_index);
+        }
+
+        public static void Decrypt(Span<byte> data, Span<byte> key_table, SpriteDecryptParams decry_params, long base_index = 0)
+        {
+            if (key_table.Length != KeyTableSize)
+                ThrowInvalidKeyTable();
+            
+            for (int i = 0; i < data.Length; i++)
+            {
+                long key_index = base_index + i;
+                byte current_byte = data[i];
+                current_byte ^= key_table[(int)(key_index % decry_params.DecryMod1)];
+                current_byte += decry_params.DecryAdd;
+                current_byte += key_table[(int)(key_index % decry_params.DecryMod2)];
+                current_byte ^= decry_params.DecryXor;
+                data[i] = current_byte;
+            }
+        }
+        
+        public static void GenerateKeyTable(Span<byte> key_table, uint seed, in SpriteDecryptParams decry_params)
+        {
+            if (key_table.Length != KeyTableSize)
+                ThrowInvalidKeyTable();
+            
+            uint state1 = seed * decry_params.GenKeyInitMul + decry_params.GenKeyInitAdd;
+            uint state2 = (state1 << decry_params.GenKeyInitShift) ^ state1;
+            for (int i = 0; i < KeyTableSize; i++)
+            {
+                state1 -= seed;
+                state1 += state2;
+                state2 = state1 + decry_params.GenKeyRoundAdd;
+                state1 *= state2 & decry_params.GenKeyRoundAnd;
+                key_table[i] = (byte)state1;
+                state1 >>= decry_params.GenKeyRoundShift;
+            }
+        }
+        
+        private static void ThrowInvalidKeyTable()
+        {
+            throw new ArgumentException($"Key table must be exactly {KeyTableSize} bytes long.");
+        }
+    }
+
+    public class SpriteDecryptionStream : Stream
+    {
+        private readonly Stream m_base_stream;
+        private readonly byte[] m_key_table;
+        private readonly SpriteDecryptParams m_decry_params;
+        
+        public SpriteDecryptionStream(Stream encrypted_source, uint decryption_key, SpriteDecryptParams decry_params)
+        {
+            m_base_stream = encrypted_source;
+            m_decry_params = decry_params;
+            
+            m_key_table = new byte[SpriteDecryptionUtils.KeyTableSize];
+            SpriteDecryptionUtils.GenerateKeyTable(m_key_table, decryption_key, decry_params);
+        }
+
+        public override void Flush()
+        {
+            m_base_stream.Flush();
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            return m_base_stream.Seek(offset, origin);
+        }
+
+        public override void SetLength(long value)
+        {
+            m_base_stream.SetLength(value);
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            long init_position = m_base_stream.Position;
+            int bytes_read = m_base_stream.Read(buffer, offset, count);
+
+            if (bytes_read == 0)
+                return 0;
+            
+            var span = new Span<byte>(buffer, offset, bytes_read);
+            SpriteDecryptionUtils.Decrypt(span, m_key_table, m_decry_params, (int)init_position);
+
+            return bytes_read;
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            throw new NotImplementedException("SpriteDecryptionStream does not support writing yet.");
+        }
+
+        public override bool CanRead => m_base_stream.CanRead;
+        public override bool CanSeek => m_base_stream.CanSeek;
+        public override bool CanWrite => false;  // Unimplemented for writing
+
+        public override long Length => m_base_stream.Length;
+
+        public override long Position
+        {
+            get => m_base_stream.Position;
+            set => m_base_stream.Position = value;
+        }
+    }
+}
\ No newline at end of file
diff --git a/ArcFormats/Resources/Formats.dat b/ArcFormats/Resources/Formats.dat
index ae3a873d..75788782 100644
Binary files a/ArcFormats/Resources/Formats.dat and b/ArcFormats/Resources/Formats.dat differ