diff --git a/ArcFormats/Entis/ArcPAC.cs b/ArcFormats/Entis/ArcPAC.cs
new file mode 100644
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+++ b/ArcFormats/Entis/ArcPAC.cs
@@ -0,0 +1,100 @@
+//! \file       ArcPAC.cs
+//! \date       Sun Jan 08 11:43:23 2017
+//! \brief      Terios resource archive.
+//
+// Copyright (C) 2017 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;
+using System.Collections.Generic;
+using System.ComponentModel.Composition;
+using System.IO;
+
+namespace GameRes.Formats.Entis
+{
+    /// <summary>
+    /// Archive format used in Teri☆Mix
+    /// </summary>
+    [Export(typeof(ArchiveFormat))]
+    public class PacOpener : ArchiveFormat
+    {
+        public override string         Tag { get { return "PAC/TERIOS"; } }
+        public override string Description { get { return "Terios resource archive"; } }
+        public override uint     Signature { get { return 0; } }
+        public override bool  IsHierarchic { get { return false; } }
+        public override bool      CanWrite { get { return false; } }
+
+        static readonly byte[] DefaultPassword = Encodings.cp932.GetBytes ("パブロ・ディエゴ・ホセ・フランチスコ・ド・ポール・ジャン・ネボムチェーノ・クリスバン・ クリスピアノ・ド・ラ・ンチシュ・トリニダット・ルイス・イ・ピカソのシプリアーノ･サンティシマ･トリニダードは三位一体の事だったりする");
+
+        public override ArcFile TryOpen (ArcView file)
+        {
+            if (!file.Name.EndsWith (".pac", StringComparison.InvariantCultureIgnoreCase))
+                return null;
+            uint index_offset = 0;
+            var name_buf = new byte[0x18];
+            var dir = new List<Entry>();
+            while (index_offset < file.MaxOffset && dir.Count < 0x2000)
+            {
+                if (0x18 != file.View.Read (index_offset, name_buf, 0, 0x18))
+                    return null;
+                if (0x20 == name_buf[0])
+                    break;
+                int name_length = 0;
+                for (name_length = 0; name_length < name_buf.Length; ++name_length)
+                {
+                    if (name_buf[name_length] < 0x20)
+                        return null;
+                    else if (0x20 == name_buf[name_length])
+                        break;
+                }
+                if (name_buf.Length == name_length)
+                    return null;
+                var name = Encodings.cp932.GetString (name_buf, 0, name_length);
+                var entry = FormatCatalog.Instance.Create<Entry> (name);
+                index_offset += 0x18;
+                entry.Offset = 0x40000 + file.View.ReadUInt32 (index_offset);
+                entry.Size = file.View.ReadUInt32 (index_offset+4);
+                if (!entry.CheckPlacement (file.MaxOffset))
+                    return null;
+                dir.Add (entry);
+                index_offset += 8;
+            }
+            if (0 == dir.Count || 0x2000 == dir.Count)
+                return null;
+            return new ArcFile (file, this, dir);
+        }
+
+        public override Stream OpenEntry (ArcFile arc, Entry entry)
+        {
+            if (0 != arc.File.View.ReadByte (entry.Offset))
+                return base.OpenEntry (arc, entry);
+            var data = arc.File.View.ReadBytes (entry.Offset+1, entry.Size-1);
+            int k = 0;
+            for (int i = 0; i < data.Length; ++i)
+            {
+                data[i] ^= (byte)~DefaultPassword[k++];
+                if (k >= DefaultPassword.Length)
+                    k = 0;
+            }
+            return new BinMemoryStream (data, entry.Name);
+        }
+    }
+}