diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj
index 3fe5eb79..859bbce1 100644
--- a/ArcFormats/ArcFormats.csproj
+++ b/ArcFormats/ArcFormats.csproj
@@ -350,6 +350,7 @@
     <Compile Include="Leaf\ArcAR2.cs" />
     <Compile Include="Leaf\ArcLEAF.cs" />
     <Compile Include="Leaf\ArcPAK.cs" />
+    <Compile Include="Leaf\ArcSDAT.cs" />
     <Compile Include="Leaf\AudioP16.cs" />
     <Compile Include="Leaf\ImageBJR.cs" />
     <Compile Include="Leaf\ImageLFG.cs" />
diff --git a/ArcFormats/Leaf/ArcSDAT.cs b/ArcFormats/Leaf/ArcSDAT.cs
new file mode 100644
index 00000000..b4829190
--- /dev/null
+++ b/ArcFormats/Leaf/ArcSDAT.cs
@@ -0,0 +1,86 @@
+//! \file       ArcSDAT.cs
+//! \date       2026-04-16
+//! \brief      AQUAPLUS resource archive.
+//
+// Copyright (C) 2026 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;
+using System.Text;
+
+namespace GameRes.Formats.Leaf {
+    [Export(typeof(ArchiveFormat))]
+    public class SDatOpener : ArchiveFormat {
+        public override string         Tag => "SDAT";
+        public override string Description => "AQUAPLUS engine resource archive";
+        public override uint     Signature => 0x656C6946; // 'Filename'
+        public override bool  IsHierarchic => true;
+        public override bool      CanWrite => false;
+
+        public override ArcFile TryOpen(ArcView file) {
+            if (!file.View.AsciiEqual(4, "name    "))
+                return null; // TODO: it is said that only Steam ver has these spaces
+            uint section_size = file.View.ReadUInt32(0x0C);
+            var filenames = new List<KeyValuePair<uint, string>>();
+            uint section_offset = 0x10, offset = section_offset;
+            do {
+                uint name_offset = file.View.ReadUInt32(offset) + section_offset;
+                var name_buffer = new List<byte>();
+                for (int i = 0; name_offset + i < section_size; i++) {
+                    byte b = file.View.ReadByte(name_offset + i);
+                    if (b == 0)
+                        break;
+                    name_buffer.Add(b);
+                }
+                string name = Encoding.UTF8.GetString(name_buffer.ToArray());
+                if (name.StartsWith(@"\"))
+                    name = name.Substring(1);
+                filenames.Add(new KeyValuePair<uint, string>(name_offset, name));
+                offset += 4;
+            } while (offset < filenames[0].Key);
+
+            uint section_start = (uint)((section_size + 7) & ~7);
+            if (!file.View.AsciiEqual(section_start, "Pack        "))
+                return null;
+            uint count = file.View.ReadUInt32(section_start + 0x10);
+            if (count != filenames.Count)
+                return null;
+            section_size = file.View.ReadUInt32(section_start + 0x0C);
+            var dir = new List<Entry>(filenames.Count);
+            offset = section_start + 0x14;
+            for (int i = 0; i < count; i++) {
+                var entry = Create<Entry>(filenames[i].Value);
+                entry.Offset = file.View.ReadUInt32(offset);
+                entry.Size = file.View.ReadUInt32(offset + 4);
+                if (!entry.CheckPlacement(file.MaxOffset))
+                    return null;
+                if (entry.Name.HasExtension(".se") || entry.Name.HasExtension(".voice"))
+                    entry.Type = "audio";
+                dir.Add(entry);
+                offset += 8;
+            }
+            return new ArcFile(file, this, dir);
+        }
+    }
+}