diff --git a/Legacy/Rune/ArcYK.cs b/Legacy/Rune/ArcYK.cs
new file mode 100644
index 00000000..ebb294b5
--- /dev/null
+++ b/Legacy/Rune/ArcYK.cs
@@ -0,0 +1,119 @@
+//! \file       ArcYK.cs
+//! \date       2018 Mar 19
+//! \brief      Rune resource archive.
+//
+// Copyright (C) 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 System.IO;
+using System.Linq;
+using GameRes.Utility;
+
+// [000317][Rune] Yuki no Kanata
+
+namespace GameRes.Formats.Rune
+{
+    internal class YkArchive : ArcFile
+    {
+        public readonly int Key;
+
+        public YkArchive (ArcView arc, ArchiveFormat impl, ICollection<Entry> dir, int key)
+            : base (arc, impl, dir)
+        {
+            Key = key;
+        }
+    }
+
+    [Export(typeof(ArchiveFormat))]
+    public class YkOpener : ArchiveFormat
+    {
+        public override string         Tag { get { return "YK"; } }
+        public override string Description { get { return "Rune resource archive"; } }
+        public override uint     Signature { get { return 0; } }
+        public override bool  IsHierarchic { get { return true; } }
+        public override bool      CanWrite { get { return false; } }
+
+        public override ArcFile TryOpen (ArcView file)
+        {
+            if ((file.View.ReadInt32 (0) | file.View.ReadInt32 (4) | file.View.ReadInt32 (8)) != 0)
+                return null;
+            int key = file.View.ReadInt32 (0x10);
+            int count = file.View.ReadInt32 (0x14);
+            if (!IsSaneCount (count))
+                return null;
+            uint index_offset = 0x18;
+            var index = new Dictionary<int, Entry> (count);
+            for (int i = 0; i < count; ++i)
+            {
+                int id = file.View.ReadInt32 (index_offset);
+                var entry = new Entry {
+                    Offset = file.View.ReadUInt32 (index_offset+4),
+                    Size   = file.View.ReadUInt32 (index_offset+8),
+                };
+                if (!entry.CheckPlacement (file.MaxOffset))
+                    return null;
+                index[id] = entry;
+                index_offset += 12;
+            }
+            var names_entry = index[0];
+            var names = file.View.ReadBytes (names_entry.Offset, names_entry.Size);
+            if (key != 0)
+                DecryptData (names, key);
+            using (var input = new BinMemoryStream (names))
+            {
+                while (input.PeekByte() != -1)
+                {
+                    int id = input.ReadInt32();
+                    var name = input.ReadCString();
+                    if (!string.IsNullOrEmpty (name))
+                    {
+                        var entry = index[id];
+                        entry.Name = name;
+                        entry.Type = FormatCatalog.Instance.GetTypeFromName (name);
+                    }
+                }
+            }
+            var dir = index.Values.Where (e => !string.IsNullOrEmpty (e.Name)).ToList();
+            return new YkArchive (file, this, dir, key);
+        }
+
+        public override Stream OpenEntry (ArcFile arc, Entry entry)
+        {
+            var yarc = arc as YkArchive;
+            if (null == yarc || 0 == yarc.Key)
+                return base.OpenEntry (arc, entry);
+            var data = arc.File.View.ReadBytes (entry.Offset, entry.Size);
+            DecryptData (data, yarc.Key);
+            return new BinMemoryStream (data, entry.Name);
+        }
+
+        void DecryptData (byte[] data, int key)
+        {
+            for (int i = 0; i < data.Length; ++i)
+            {
+                uint shift = (uint)(92 * key * i * (i + key));
+                data[i] = Binary.RotByteL (data[i], (int)(7 - shift % 7));
+            }
+        }
+    }
+}