diff --git a/language-change/Makefile b/language-change/Makefile
new file mode 100644
index 0000000..cf67497
--- /dev/null
+++ b/language-change/Makefile
@@ -0,0 +1,12 @@
+APP_NAME = language-change.exe
+
+all: build
+
+build:
+	go build -o $(APP_NAME) ./
+
+run: build
+	./$(APP_NAME)
+
+clean:
+	rm -f $(APP_NAME)
diff --git a/language-change/asset-meta/bytehash16.go b/language-change/asset-meta/bytehash16.go
new file mode 100644
index 0000000..eb0823c
--- /dev/null
+++ b/language-change/asset-meta/bytehash16.go
@@ -0,0 +1,30 @@
+package assetMeta
+
+import (
+	"fmt"
+	"io"
+)
+
+type ByteHash16 []byte
+
+func ByteHash16FromBytes(r io.ReadSeeker) (ByteHash16, error) {
+	fullHash := make([]byte, 16)
+	buf := make([]byte, 4)
+	for i := 0; i < 4; i++ {
+		if _, err := io.ReadFull(r, buf); err != nil {
+			return nil, err
+		}
+		for j := 0; j < 4; j++ {
+			fullHash[i*4+j] = buf[3-j]
+		}
+	}
+	return ByteHash16(fullHash), nil
+}
+
+func (b ByteHash16) String() string {
+	s := ""
+	for _, v := range b {
+		s += fmt.Sprintf("%02x", v)
+	}
+	return s
+}
diff --git a/language-change/asset-meta/dataEntry.go b/language-change/asset-meta/dataEntry.go
new file mode 100644
index 0000000..3943998
--- /dev/null
+++ b/language-change/asset-meta/dataEntry.go
@@ -0,0 +1,28 @@
+package assetMeta
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+type DataEntry struct {
+	NameHash int32
+	Size     uint32
+	Offset   uint32
+}
+
+func DataEntryFromBytes(r io.Reader) (*DataEntry, error) {
+	var d DataEntry
+
+	if err := binary.Read(r, binary.BigEndian, &d.NameHash); err != nil {
+		return nil, err
+	}
+	if err := binary.Read(r, binary.BigEndian, &d.Size); err != nil {
+		return nil, err
+	}
+	if err := binary.Read(r, binary.BigEndian, &d.Offset); err != nil {
+		return nil, err
+	}
+
+	return &d, nil
+}
diff --git a/language-change/asset-meta/designIndex.go b/language-change/asset-meta/designIndex.go
new file mode 100644
index 0000000..c1576f3
--- /dev/null
+++ b/language-change/asset-meta/designIndex.go
@@ -0,0 +1,98 @@
+package assetMeta
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+
+type DesignIndex struct {
+	UnkI64          int64
+	FileCount       int32
+	DesignDataCount int32
+	FileList        []FileEntry
+}
+
+
+
+func (d *DesignIndex) FindDataAndFileByTarget(target int32) (DataEntry, FileEntry, error) {
+	for _, file := range d.FileList {
+		for _, entry := range file.DataEntries {
+			if entry.NameHash == target {
+				return entry, file, nil
+			}
+		}
+	}
+	return DataEntry{}, FileEntry{}, errors.New("not found")
+}
+
+
+func DesignIndexFromBytes(assetFolder string, indexHash string) (*DesignIndex, error) {
+	path := filepath.Join(assetFolder, fmt.Sprintf("DesignV_%s.bytes", indexHash))
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	r := bytes.NewReader(data)
+
+	var d DesignIndex
+
+	if err := binary.Read(r, binary.BigEndian, &d.UnkI64); err != nil {
+		return nil, err
+	}
+	if err := binary.Read(r, binary.BigEndian, &d.FileCount); err != nil {
+		return nil, err
+	}
+	if err := binary.Read(r, binary.BigEndian, &d.DesignDataCount); err != nil {
+		return nil, err
+	}
+
+	d.FileList = make([]FileEntry, 0, d.FileCount)
+	for i := int32(0); i < d.FileCount; i++ {
+		entry, err := FileEntryFromBytes(r)
+		if err != nil {
+			return nil, err
+		}
+		d.FileList = append(d.FileList, *entry)
+	}
+
+	return &d, nil
+}
+
+
+func GetIndexHash(assetFolder string) (string, error) {
+	path := filepath.Join(assetFolder, "M_DesignV.bytes")
+
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	_, err = f.Seek(0x1C, 0)
+	if err != nil {
+		return "", err
+	}
+
+	hash := make([]byte, 0x10)
+	index := 0
+	for i := 0; i < 4; i++ {
+		chunk := make([]byte, 4)
+		_, err := f.Read(chunk)
+		if err != nil {
+			return "", err
+		}
+
+		for bytePos := 3; bytePos >= 0; bytePos-- {
+			hash[index] = chunk[bytePos]
+			index++
+		}
+	}
+
+	return hex.EncodeToString(hash), nil
+}
\ No newline at end of file
diff --git a/language-change/asset-meta/fileEntry.go b/language-change/asset-meta/fileEntry.go
new file mode 100644
index 0000000..a7c1cdc
--- /dev/null
+++ b/language-change/asset-meta/fileEntry.go
@@ -0,0 +1,63 @@
+package assetMeta
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+type FileEntry struct {
+	NameHash       int32
+	FileByteName   string
+	Size           int64
+	DataCount      int32
+	DataEntries    []DataEntry
+	Unk            uint8
+}
+
+func FileEntryFromBytes(r io.Reader) (*FileEntry, error) {
+	var f FileEntry
+
+	if err := binary.Read(r, binary.BigEndian, &f.NameHash); err != nil {
+		return nil, err
+	}
+
+	buf := make([]byte, 16)
+	if _, err := io.ReadFull(r, buf); err != nil {
+		return nil, err
+	}
+	f.FileByteName = toHex(buf)
+
+	if err := binary.Read(r, binary.BigEndian, &f.Size); err != nil {
+		return nil, err
+	}
+	if err := binary.Read(r, binary.BigEndian, &f.DataCount); err != nil {
+		return nil, err
+	}
+
+	f.DataEntries = make([]DataEntry, 0, f.DataCount)
+	for i := int32(0); i < f.DataCount; i++ {
+		entry, err := DataEntryFromBytes(r)
+		if err != nil {
+			return nil, err
+		}
+		f.DataEntries = append(f.DataEntries, *entry)
+	}
+
+	// read 1 byte
+	b := make([]byte, 1)
+	if _, err := r.Read(b); err != nil {
+		return nil, err
+	}
+	f.Unk = b[0]
+
+	return &f, nil
+}
+
+func toHex(buf []byte) string {
+	s := ""
+	for _, b := range buf {
+		s += fmt.Sprintf("%02x", b)
+	}
+	return s
+}
diff --git a/language-change/asset-meta/miniAsset.go b/language-change/asset-meta/miniAsset.go
new file mode 100644
index 0000000..5b67910
--- /dev/null
+++ b/language-change/asset-meta/miniAsset.go
@@ -0,0 +1,32 @@
+package assetMeta
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+type MiniAsset struct {
+	RevisionID      uint32
+	DesignIndexHash ByteHash16
+}
+
+func MiniAssetFromBytes(r io.ReadSeeker) (*MiniAsset, error) {
+	if _, err := r.Seek(6*4, io.SeekCurrent); err != nil {
+		return nil, err
+	}
+
+	var revID uint32
+	if err := binary.Read(r, binary.LittleEndian, &revID); err != nil {
+		return nil, err
+	}
+
+	hash, err := ByteHash16FromBytes(r)
+	if err != nil {
+		return nil, err
+	}
+
+	return &MiniAsset{
+		RevisionID:      revID,
+		DesignIndexHash: hash,
+	}, nil
+}
diff --git a/language-change/excel-language/patch.go b/language-change/excel-language/patch.go
new file mode 100644
index 0000000..095df84
--- /dev/null
+++ b/language-change/excel-language/patch.go
@@ -0,0 +1,114 @@
+package excelLanguage
+
+import (
+	"bytes"
+	"io"
+	assetMeta "language-change/asset-meta"
+	"os"
+	"path/filepath"
+)
+
+type ExcelLanguage struct {
+	AssetFolder    string
+	ExcelDataEntry *assetMeta.DataEntry
+	ExcelFileEntry *assetMeta.FileEntry
+}
+
+func NewExcelLanguage(assetFolder string, dataEntry *assetMeta.DataEntry, fileEntry *assetMeta.FileEntry) *ExcelLanguage {
+	return &ExcelLanguage{
+		AssetFolder:    assetFolder,
+		ExcelDataEntry: dataEntry,
+		ExcelFileEntry: fileEntry,
+	}
+}
+
+func (a *ExcelLanguage) Unmarshal(rows []LanguageRow) ([]byte, error) {
+	buf := new(bytes.Buffer)
+
+	buf.WriteByte(0)
+	if err := writeI8Varint(buf, int8(len(rows))); err != nil {
+		return nil, err
+	}
+
+	for _, row := range rows {
+		rowData, err := row.Unmarshal()
+		if err != nil {
+			return nil, err
+		}
+		if _, err := buf.Write(rowData); err != nil {
+			return nil, err
+		}
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (a *ExcelLanguage) Parse() ([]LanguageRow, error) {
+	excelPath := filepath.Join(a.AssetFolder, a.ExcelFileEntry.FileByteName+".bytes")
+
+	f, err := os.Open(excelPath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	if _, err := f.Seek(int64(a.ExcelDataEntry.Offset), io.SeekStart); err != nil {
+		return nil, err
+	}
+
+	buffer := make([]byte, a.ExcelDataEntry.Size)
+	if _, err := io.ReadFull(f, buffer); err != nil {
+		return nil, err
+	}
+
+	reader := bytes.NewReader(buffer)
+
+	_, _ = reader.ReadByte() // skip first byte
+	count, err := readI8Varint(reader)
+	if err != nil {
+		return nil, err
+	}
+
+	rows := make([]LanguageRow, 0, count)
+	for i := 0; i < count; i++ {
+		bitmask, err := reader.ReadByte()
+		if err != nil {
+			return nil, err
+		}
+
+		row := LanguageRow{}
+
+		if bitmask&(1<<0) != 0 {
+			s, err := readString(reader)
+			if err != nil {
+				return nil, err
+			}
+			row.Area = &s
+		}
+		if bitmask&(1<<1) != 0 {
+			t, err := reader.ReadByte()
+			if err != nil {
+				return nil, err
+			}
+			row.Type = &t
+		}
+		if bitmask&(1<<2) != 0 {
+			arr, err := readStringArray(reader)
+			if err != nil {
+				return nil, err
+			}
+			row.LanguageList = arr
+		}
+		if bitmask&(1<<3) != 0 {
+			s, err := readString(reader)
+			if err != nil {
+				return nil, err
+			}
+			row.DefaultLanguage = &s
+		}
+
+		rows = append(rows, row)
+	}
+
+	return rows, nil
+}
diff --git a/language-change/excel-language/row.go b/language-change/excel-language/row.go
new file mode 100644
index 0000000..51d648f
--- /dev/null
+++ b/language-change/excel-language/row.go
@@ -0,0 +1,81 @@
+package excelLanguage
+
+import (
+	"bytes"
+	"errors"
+)
+
+type LanguageRow struct {
+	Area            *string
+	Type            *uint8
+	LanguageList    []string
+	DefaultLanguage *string
+}
+
+func (r *LanguageRow) Unmarshal() ([]byte, error) {
+	buf := new(bytes.Buffer)
+
+	var bitmask uint8
+	if r.Area != nil {
+		bitmask |= 1 << 0
+	}
+	if r.Type != nil {
+		bitmask |= 1 << 1
+	}
+	if len(r.LanguageList) > 0 {
+		bitmask |= 1 << 2
+	}
+	if r.DefaultLanguage != nil {
+		bitmask |= 1 << 3
+	}
+
+	if err := buf.WriteByte(bitmask); err != nil {
+		return nil, err
+	}
+
+	if r.Area != nil {
+		if err := writeString(buf, *r.Area); err != nil {
+			return nil, err
+		}
+	}
+	if r.Type != nil {
+		if err := buf.WriteByte(*r.Type); err != nil {
+			return nil, err
+		}
+	}
+	if len(r.LanguageList) > 0 {
+		if err := writeStringArray(buf, r.LanguageList); err != nil {
+			return nil, err
+		}
+	}
+	if r.DefaultLanguage != nil {
+		if err := writeString(buf, *r.DefaultLanguage); err != nil {
+			return nil, err
+		}
+	}
+
+	return buf.Bytes(), nil
+}
+
+func writeString(buf *bytes.Buffer, s string) error {
+	if len(s) > 255 {
+		return errors.New("string too long")
+	}
+	if err := buf.WriteByte(uint8(len(s))); err != nil {
+		return err
+	}
+	_, err := buf.Write([]byte(s))
+	return err
+}
+
+func writeStringArray(buf *bytes.Buffer, arr []string) error {
+	if err := writeI8Varint(buf, int8(len(arr))); err != nil {
+		return err
+	}
+	for _, s := range arr {
+		if err := writeString(buf, s); err != nil {
+			return err
+		}
+	}
+	return nil
+}
diff --git a/language-change/excel-language/utils.go b/language-change/excel-language/utils.go
new file mode 100644
index 0000000..e1fd4c6
--- /dev/null
+++ b/language-change/excel-language/utils.go
@@ -0,0 +1,53 @@
+package excelLanguage
+
+import (
+	"bytes"
+	"encoding/binary"
+	"io"
+)
+
+func writeI8Varint(buf *bytes.Buffer, v int8) error {
+	uv := uint64((uint32(v) << 1) ^ uint32(v>>7)) // zigzag encode
+	b := make([]byte, binary.MaxVarintLen64)
+	n := binary.PutUvarint(b, uv)
+	_, err := buf.Write(b[:n])
+	return err
+}
+
+func readI8Varint(r *bytes.Reader) (int, error) {
+	uv, err := binary.ReadUvarint(r)
+	if err != nil {
+		return 0, err
+	}
+	// zigzag decode
+	v := int((uv >> 1) ^ uint64((int64(uv&1)<<63)>>63))
+	return v, nil
+}
+
+func readString(r *bytes.Reader) (string, error) {
+	l, err := r.ReadByte()
+	if err != nil {
+		return "", err
+	}
+	buf := make([]byte, l)
+	if _, err := io.ReadFull(r, buf); err != nil {
+		return "", err
+	}
+	return string(buf), nil
+}
+
+func readStringArray(r *bytes.Reader) ([]string, error) {
+	length, err := readI8Varint(r)
+	if err != nil {
+		return nil, err
+	}
+	arr := make([]string, 0, length)
+	for i := 0; i < length; i++ {
+		s, err := readString(r)
+		if err != nil {
+			return nil, err
+		}
+		arr = append(arr, s)
+	}
+	return arr, nil
+}
\ No newline at end of file
diff --git a/language-change/go.mod b/language-change/go.mod
new file mode 100644
index 0000000..9e93a5f
--- /dev/null
+++ b/language-change/go.mod
@@ -0,0 +1,3 @@
+module language-change
+
+go 1.25.0
diff --git a/language-change/main.go b/language-change/main.go
new file mode 100644
index 0000000..6a47041
--- /dev/null
+++ b/language-change/main.go
@@ -0,0 +1,226 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	assetMeta "language-change/asset-meta"
+	excelLanguage "language-change/excel-language"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+)
+
+func isValidLang(lang string) bool {
+	valid := []string{"en", "jp", "cn", "kr"}
+	return slices.Contains(valid, lang)
+}
+
+func GetLanguage(assetPath string) (string, string, error) {
+	typeVersionGame := "cn"
+
+	indexHash, err := assetMeta.GetIndexHash(assetPath)
+	if err != nil {
+		return "", "", err
+	}
+
+	DesignIndex, err := assetMeta.DesignIndexFromBytes(assetPath, indexHash)
+	if err != nil {
+		return "", "", err
+	}
+	dataEntry, fileEntry, err := DesignIndex.FindDataAndFileByTarget(-515329346)
+	if err != nil {
+		return "", "", err
+	}
+	allowedLanguage := excelLanguage.NewExcelLanguage(assetPath, &dataEntry, &fileEntry)
+	languageRows, err := allowedLanguage.Parse()
+	if err != nil {
+		return "", "", err
+	}
+
+	currentTextLang := ""
+	currentVoiceLang := ""
+
+	pairs := []struct {
+		area string
+		typ  *uint8
+	}{
+		{"os", nil},
+		{"cn", func() *uint8 { v := uint8(1); return &v }()},
+		{"os", func() *uint8 { v := uint8(1); return &v }()},
+		{"cn", nil},
+	}
+
+	for _, p := range pairs {
+		var found *excelLanguage.LanguageRow
+		for i := range languageRows {
+			if languageRows[i].Area != nil && *languageRows[i].Area == p.area {
+				if (languageRows[i].Type == nil && p.typ == nil) ||
+					(languageRows[i].Type != nil && p.typ != nil && *languageRows[i].Type == *p.typ) {
+					found = &languageRows[i]
+					break
+				}
+			}
+		}
+		if found == nil {
+			continue
+		}
+		if found.DefaultLanguage != nil && found.Area != nil && *found.Area == typeVersionGame && found.Type == nil {
+			currentTextLang = *found.DefaultLanguage
+		}
+		if found.DefaultLanguage != nil && found.Area != nil && *found.Area == typeVersionGame && found.Type != nil {
+			currentVoiceLang = *found.DefaultLanguage
+		}
+	}
+
+	if currentTextLang == "" || currentVoiceLang == "" || !isValidLang(currentTextLang) || !isValidLang(currentVoiceLang) {
+		return "", "", errors.New("not found language")
+	}
+
+	return currentTextLang, currentVoiceLang, nil
+}
+
+func SetLanguage(assetPath string, text, voice string) error {
+	indexHash, err := assetMeta.GetIndexHash(assetPath)
+	if err != nil {
+		return err
+	}
+
+	DesignIndex, err := assetMeta.DesignIndexFromBytes(assetPath, indexHash)
+	if err != nil {
+		return err
+	}
+
+	dataEntry, fileEntry, err := GetAssetData(DesignIndex, "AllowedLanguage")
+	if err != nil {
+		return err
+	}
+	allowedLanguage := excelLanguage.NewExcelLanguage(assetPath, dataEntry, fileEntry)
+	languageRows, err := allowedLanguage.Parse()
+	if err != nil {
+		return err
+	}
+
+	pairs := []struct {
+		area string
+		typ  *uint8
+		lang string
+	}{
+		{"os", nil, text},
+		{"cn", func() *uint8 { v := uint8(1); return &v }(), voice},
+		{"os", func() *uint8 { v := uint8(1); return &v }(), voice},
+		{"cn", nil, text},
+	}
+
+	for _, p := range pairs {
+		var found *excelLanguage.LanguageRow
+		for i := range languageRows {
+			if languageRows[i].Area != nil && *languageRows[i].Area == p.area {
+				if (languageRows[i].Type == nil && p.typ == nil) ||
+					(languageRows[i].Type != nil && p.typ != nil && *languageRows[i].Type == *p.typ) {
+					found = &languageRows[i]
+					break
+				}
+			}
+		}
+		if found == nil {
+			continue
+		}
+
+		found.DefaultLanguage = &p.lang
+		found.LanguageList = []string{p.lang}
+	}
+
+	data, err := allowedLanguage.Unmarshal(languageRows)
+	if err != nil {
+		return err
+	}
+
+	filePath := filepath.Join(assetPath, fileEntry.FileByteName+".bytes")
+
+	f, err := os.OpenFile(filePath, os.O_RDWR, 0644)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	if _, err := f.Seek(int64(dataEntry.Offset), 0); err != nil {
+		return err
+	}
+	if _, err := f.Write(data); err != nil {
+		return err
+	}
+
+	if len(data) < int(dataEntry.Size) {
+		remaining := int(dataEntry.Size) - len(data)
+		zeros := bytes.Repeat([]byte{0}, remaining)
+		if _, err := f.Write(zeros); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func main() {
+	reader := bufio.NewReader(os.Stdin)
+	fmt.Print("Enter source DesignData folder path: ")
+	source, _ := reader.ReadString('\n')
+	source = strings.TrimSpace(source)
+	if source == "" {
+		fmt.Fprintln(os.Stderr, "no source folder provided")
+		os.Exit(1)
+	}
+
+	info, err := os.Stat(source)
+	if os.IsNotExist(err) {
+		fmt.Fprintln(os.Stderr, "source folder does not exist")
+		os.Exit(1)
+	}
+
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "error accessing path:", err)
+		os.Exit(1)
+	}
+
+	if !info.IsDir() {
+		fmt.Fprintln(os.Stderr, "path is not a directory")
+		os.Exit(1)
+	}
+
+
+	currentTextLang, currentVoiceLang, err := GetLanguage(source)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "error getting language:", err)
+		os.Exit(1)
+	}
+
+	fmt.Println("Current language:", currentTextLang, currentVoiceLang)
+
+	fmt.Println("Allow languages: en, jp, cn, kr")
+
+	fmt.Print("Enter text language: ")
+	textLang, _ := reader.ReadString('\n')
+	textLang = strings.TrimSpace(textLang)
+	if textLang == "" {
+		fmt.Fprintln(os.Stderr, "no text language provided")
+		os.Exit(1)
+	}
+
+	fmt.Print("Enter voice language: ")
+	voiceLang, _ := reader.ReadString('\n')
+	voiceLang = strings.TrimSpace(voiceLang)
+	if voiceLang == "" {
+		fmt.Fprintln(os.Stderr, "no voice language provided")
+		os.Exit(1)
+	}
+
+	if err := SetLanguage(source, textLang, voiceLang); err != nil {
+		fmt.Fprintln(os.Stderr, "error setting language:", err)
+		os.Exit(1)
+	}
+
+	fmt.Println("Language set successfully.")
+
+}
diff --git a/language-change/ulils.go b/language-change/ulils.go
new file mode 100644
index 0000000..67e958f
--- /dev/null
+++ b/language-change/ulils.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"errors"
+	assetMeta "language-change/asset-meta"
+)
+
+func Get32BitHashConst(s string) int32 {
+	var hash1 int32 = 5381
+	var hash2 int32 = hash1
+
+	bytes := []byte(s)
+	length := len(bytes)
+
+	for i := 0; i < length; i += 2 {
+		hash1 = ((hash1 << 5) + hash1) ^ int32(bytes[i])
+		if i+1 < length {
+			hash2 = ((hash2 << 5) + hash2) ^ int32(bytes[i+1])
+		}
+	}
+
+	return int32(uint32(hash1) + uint32(hash2)*1566083941)
+}
+
+func GetAssetData(assets *assetMeta.DesignIndex, name string) (*assetMeta.DataEntry, *assetMeta.FileEntry, error) {
+	dataEntry, fileEntry, err := assets.FindDataAndFileByTarget(Get32BitHashConst("BakedConfig/ExcelOutput/" + name + ".bytes"))
+	if err == nil {
+		return &dataEntry, &fileEntry, nil
+	}
+	dataEntry, fileEntry, err = assets.FindDataAndFileByTarget(Get32BitHashConst("BakedConfig/ExcelOutputGameCore/" + name + ".bytes"))
+	if err == nil {
+		return &dataEntry, &fileEntry, nil
+	}
+	dataEntry, fileEntry, err = assets.FindDataAndFileByTarget(Get32BitHashConst("BakedConfig/ExcelOutputAdventureGame/" + name + ".bytes"))
+	if err == nil {
+		return &dataEntry, &fileEntry, nil
+	}
+	return nil, nil, errors.New("not found")
+}