diff --git a/Regions/junishiscripts_Region Rename.lua b/Regions/junishiscripts_Region Rename.lua
new file mode 100644
index 000000000..53e5bbd57
--- /dev/null
+++ b/Regions/junishiscripts_Region Rename.lua	
@@ -0,0 +1,165 @@
+-- @description Region Rename
+-- @author Junishi Scripts
+-- @version 1.0
+-- @link X https://x.com/1496jun
+-- @about
+--   - Overview
+--   This script provides a GUI to rename all regions within the current time selection in REAPER. It offers flexible naming options, including replacement or prefix/suffix modes, and supports sequential numbering or alphabet labels (upper/lower case).
+--
+--   - How to Use
+--   Select a time range in REAPER that includes the regions you want to rename.
+--   Run the script from the Actions List.
+--   A GUI window titled "Rename Regions (Time Selection)" will appear.
+--
+--   - GUI Options
+--   Base Name
+--   Enter the text that will serve as the base for the new region names.
+--
+--   --- Mode
+--   Replace: Replace existing region names entirely.
+--   Add as Prefix: Add the base name and sequence before existing names.
+--   Add as Suffix: Add the base name and sequence after existing names.
+--
+--   --- Sequence Type
+--   none: No numbering or lettering.
+--   number: Adds a numeric counter (e.g. 01, 02...).
+--   alphabet (upper): Adds uppercase letters (e.g. A, B, C...).
+--   alphabet (lower): Adds lowercase letters (e.g. a, b, c...).
+--
+--   --- Digits
+--   Number of digits or letters to pad the sequence (e.g. 02, AA).
+--
+--   --- Applying Changes
+--   Click "Apply" to rename all regions within the current time selection using the selected settings.
+--
+--
+--   - Notes
+--   The script only affects regions, not markers.
+--   Only regions overlapping the current time selection are renamed.
+--   Settings persist between script executions.
+
+-- @description Rename Regions with Full GUI (ReaImGui, alphabet case merged)
+-- @version 1.0.0
+-- @author 1496jun https://x.com/1496jun
+-- @requires ReaImGui
+
+local ctx = reaper.ImGui_CreateContext('Region Renamer')
+local section = "RenameRegionsTool"
+
+local function get_state(key, default)
+  local v = reaper.GetExtState(section, key)
+  return v ~= "" and v or default
+end
+
+local base_name    = get_state("BaseName", "")
+local mode_items   = {"Replace", "Add as Prefix", "Add as Suffix"}
+local mode_index   = tonumber(get_state("ModeIndex", "0"))
+
+-- 統合された選択肢
+local seq_labels = {"none", "number", "alphabet (upper)", "alphabet (lower)"}
+local seq_values = {"none", "num", "alpha_upper", "alpha_lower"}
+local seq_index  = tonumber(get_state("SeqTypeIndex", "0"))
+
+local digits     = tonumber(get_state("Digits", "2"))
+
+-- アルファベット連番
+local function get_alpha(index, digits, to_upper)
+  index = index - 1
+  local chars = {}
+  local base = to_upper and 65 or 97
+  repeat
+    local remainder = index % 26
+    table.insert(chars, 1, string.char(base + remainder))
+    index = math.floor(index / 26) - 1
+  until index < 0
+  local result = table.concat(chars)
+  if #result < digits then
+    result = string.rep(string.char(base), digits - #result) .. result
+  end
+  return result
+end
+
+local function rename_regions()
+  local start_time, end_time = reaper.GetSet_LoopTimeRange(false, false, 0, 0, false)
+  local retval = reaper.CountProjectMarkers(0)
+  local regions = {}
+
+  for i = 0, retval - 1 do
+    local _, isrgn, pos, rgnend, name, idx = reaper.EnumProjectMarkers(i)
+    if isrgn and pos < end_time and rgnend > start_time then
+      table.insert(regions, {idx = idx, pos = pos, rgnend = rgnend, name = name})
+    end
+  end
+
+  reaper.Undo_BeginBlock()
+  for i, region in ipairs(regions) do
+    local suffix = ""
+    local seq_type = seq_values[seq_index + 1]
+
+    if seq_type == "num" then
+      suffix = string.format("%0" .. digits .. "d", i)
+    elseif seq_type == "alpha_upper" then
+      suffix = get_alpha(i, digits, true)
+    elseif seq_type == "alpha_lower" then
+      suffix = get_alpha(i, digits, false)
+    end
+
+    local new_name = ""
+    if mode_index == 0 then
+      new_name = base_name .. suffix
+    elseif mode_index == 1 then
+      new_name = base_name .. region.name .. suffix
+    elseif mode_index == 2 then
+      new_name = region.name .. base_name .. suffix
+    end
+
+    reaper.SetProjectMarker(region.idx, true, region.pos, region.rgnend, new_name)
+  end
+
+  reaper.Undo_EndBlock("Rename regions (GUI)", -1)
+  reaper.UpdateArrange()
+end
+
+-- GUIループ
+local function loop()
+  reaper.ImGui_SetNextWindowSize(ctx, 460, 250, reaper.ImGui_Cond_FirstUseEver())
+  local visible, open = reaper.ImGui_Begin(ctx, 'Rename Regions (Time Selection)', true)
+
+  if visible then
+    reaper.ImGui_Text(ctx, "Rename regions inside current time selection.")
+    _, base_name = reaper.ImGui_InputText(ctx, "Base Name", base_name)
+
+    reaper.ImGui_Separator(ctx)
+
+    _, mode_index = reaper.ImGui_Combo(ctx, "Mode", mode_index, table.concat(mode_items, "\0") .. "\0")
+    _, seq_index  = reaper.ImGui_Combo(ctx, "Sequence Type", seq_index, table.concat(seq_labels, "\0") .. "\0")
+
+    _, digits = reaper.ImGui_InputInt(ctx, "Digits", digits)
+    if digits < 1 then digits = 1 end
+
+    reaper.ImGui_Separator(ctx)
+
+    if reaper.ImGui_Button(ctx, "Apply") then
+      rename_regions()
+      reaper.SetExtState(section, "BaseName", base_name, true)
+      reaper.SetExtState(section, "ModeIndex", tostring(mode_index), true)
+      reaper.SetExtState(section, "SeqTypeIndex", tostring(seq_index), true)
+      reaper.SetExtState(section, "Digits", tostring(digits), true)
+      open = false -- ウィンドウを閉じる
+    end
+  end
+
+  reaper.ImGui_End(ctx)
+
+  if open then
+    reaper.defer(loop)
+  else
+    if ctx and reaper.ImGui_DestroyContext then
+      pcall(reaper.ImGui_DestroyContext, ctx)
+      ctx = nil
+    end
+  end
+end
+
+reaper.defer(loop)
+