diff --git a/PKHeX.Core/Saves/Substructures/Gen4/Dendou4.cs b/PKHeX.Core/Saves/Substructures/Gen4/Dendou4.cs
new file mode 100644
index 000000000..e50984b7f
--- /dev/null
+++ b/PKHeX.Core/Saves/Substructures/Gen4/Dendou4.cs
@@ -0,0 +1,119 @@
+using System;
+using static System.Buffers.Binary.BinaryPrimitives;
+
+namespace PKHeX.Core;
+
+public sealed class Dendou4
+{
+    private const int SIZE = 0x2AB0;
+    private const int SIZE_FOOTER = 0x10;
+    private const int SIZE_BLOCK = 3 * 0x1000;
+
+    public const int MaxClears = 9999;
+    public const int MaxRecords = 30;
+
+    private readonly byte[] Raw;
+    private readonly int Offset;
+    private Span<byte> Data => Raw.AsSpan(Offset, SIZE_BLOCK);
+    public Dendou4(byte[] data, int offset) => (Raw, Offset) = (data, offset);
+
+    // Structure:
+    // record[30] records
+    // u32 NextIndexToOverwrite
+    // u32 ClearCount
+
+    public Dendou4Record this[int index] => GetRecord(index);
+
+    private Dendou4Record GetRecord(int index)
+    {
+        if ((uint)index >= MaxRecords)
+            throw new ArgumentOutOfRangeException(nameof(index));
+        var slice = Data.Slice(index * Dendou4Record.SIZE, Dendou4Record.SIZE);
+        return new Dendou4Record(slice);
+    }
+
+    private const int EndDataOffset = MaxRecords * Dendou4Record.SIZE; // 0x2AA8
+
+    public uint IndexNextOverwrite { get => ReadUInt32LittleEndian(Data[EndDataOffset..]); set => WriteUInt32LittleEndian(Data[EndDataOffset..], value % MaxRecords); }
+    public uint ClearCount { get => Math.Min(MaxClears, ReadUInt32LittleEndian(Data[(EndDataOffset + 4)..])); set => WriteUInt32LittleEndian(Data[(EndDataOffset + 4)..], Math.Min(MaxClears, value)); }
+
+    #region Footer
+    public bool SizeValid => BlockSize == SIZE;
+    public bool ChecksumValid => Checksum == GetChecksum();
+    public bool IsValid => SizeValid && ChecksumValid;
+
+    public uint  Magic     { get => ReadUInt32LittleEndian(Footer); set => WriteUInt32LittleEndian(Footer, value); }
+    public uint  Revision  { get => ReadUInt32LittleEndian(Footer[0x4..]); set => WriteUInt32LittleEndian(Footer[0x4..], value); }
+    public int   BlockSize { get => ReadInt32LittleEndian (Footer[0x8..]); set => WriteInt32LittleEndian (Footer[0x8..], value); }
+    public ushort BlockID  { get => ReadUInt16LittleEndian(Footer[0xC..]); set => WriteUInt16LittleEndian(Footer[0xC..], value); }
+    public ushort Checksum { get => ReadUInt16LittleEndian(Footer[0xE..]); set => WriteUInt16LittleEndian(Footer[0xE..], value); }
+
+    private ReadOnlySpan<byte> GetRegion() => Data[..(SIZE + SIZE_FOOTER)];
+    private Span<byte> Footer => Data.Slice(SIZE, SIZE_FOOTER);
+    private ushort GetChecksum() => Checksums.CRC16_CCITT(GetRegion()[..^2]);
+    public void RefreshChecksum() => Checksum = GetChecksum();
+    #endregion
+}
+
+public readonly ref struct Dendou4Record
+{
+    public const int Count = 6;
+    public const int SIZE = (Dendou4Entity.SIZE * Count) + sizeof(uint); // 0x16C
+
+    // structure:
+    // Dendou4Entity[6]
+    // u16 Year
+    // u8 Month
+    // u8 Day
+
+    private readonly Span<byte> Data;
+
+    public Dendou4Record(Span<byte> data) => Data = data;
+
+    public Dendou4Entity this[int index] => GetEntity(index);
+
+    private const int DateOffset = SIZE - 4;
+    public ushort Year { get => ReadUInt16LittleEndian(Data[DateOffset..]); set => WriteUInt16LittleEndian(Data[DateOffset..], value); }
+    public byte Month { get => Data[DateOffset + 2]; set => Data[DateOffset + 2] = value; }
+    public byte Day   { get => Data[DateOffset + 3]; set => Data[DateOffset + 3] = value; }
+
+    private Dendou4Entity GetEntity(int index)
+    {
+        if ((uint)index >= Count)
+            throw new ArgumentOutOfRangeException(nameof(index));
+        var slice = Data.Slice(index * Dendou4Entity.SIZE, Dendou4Entity.SIZE);
+        return new Dendou4Entity(slice);
+    }
+}
+
+public readonly ref struct Dendou4Entity
+{
+    public const int SIZE = 0x3C;
+    private readonly Span<byte> Data;
+
+    public Dendou4Entity(Span<byte> data) => Data = data;
+    public ushort Species { get => ReadUInt16LittleEndian(Data); set => WriteUInt16LittleEndian(Data, value); }
+    public byte Level { get => Data[2]; set => Data[2] = value; }
+    public byte Form  { get => Data[3]; set => Data[3] = value; }
+    public uint PID  { get => ReadUInt32LittleEndian(Data[4..]); set => WriteUInt32LittleEndian(Data[4..], value); }
+    public uint ID32 { get => ReadUInt32LittleEndian(Data[8..]); set => WriteUInt32LittleEndian(Data[8..], value); }
+
+    public Span<byte> Nickname_Trash => Data.Slice(0x0C, 22);
+    public Span<byte> OT_Trash => Data.Slice(0x22, 16);
+    public string Nickname
+    {
+        get => StringConverter4.GetString(Nickname_Trash);
+        set => StringConverter4.SetString(Nickname_Trash, value.AsSpan(), 10, StringConverterOption.None);
+    }
+    public string OT_Name
+    {
+        get => StringConverter4.GetString(OT_Trash);
+        set => StringConverter4.SetString(OT_Trash, value.AsSpan(), 7, StringConverterOption.None);
+    }
+
+    public ushort Move1 { get => ReadUInt16LittleEndian(Data[0x32..]); set => WriteUInt16LittleEndian(Data[0x32..], value); }
+    public ushort Move2 { get => ReadUInt16LittleEndian(Data[0x34..]); set => WriteUInt16LittleEndian(Data[0x34..], value); }
+    public ushort Move3 { get => ReadUInt16LittleEndian(Data[0x36..]); set => WriteUInt16LittleEndian(Data[0x36..], value); }
+    public ushort Move4 { get => ReadUInt16LittleEndian(Data[0x38..]); set => WriteUInt16LittleEndian(Data[0x38..], value); }
+    // u16 alignment 0x3A
+}