diff --git a/src/ui/BagMenu.lua b/src/ui/BagMenu.lua
index 3d169c0b..1205dde6 100644
--- a/src/ui/BagMenu.lua
+++ b/src/ui/BagMenu.lua
@@ -372,6 +372,8 @@ function BagMenu.new(game, opts)
   list = ListMenu.new(game, "ITEMS", buildItems(game), {
     kind = "bag",
     footer = ("¥%d"):format(game.save.money),
+    -- B returns to the start menu when the bag was opened from it
+    onCancel = opts.onCancel,
     -- SELECT reorders items like the original bag (swap_items.asm)
     onSelectKey = function(item, l)
       if not item then return end
diff --git a/src/ui/OptionsMenu.lua b/src/ui/OptionsMenu.lua
index e5c1e815..fe7f8463 100644
--- a/src/ui/OptionsMenu.lua
+++ b/src/ui/OptionsMenu.lua
@@ -328,7 +328,8 @@ local function buildRows(game)
   return rows
 end
 
-function OptionsMenu.new(game)
+function OptionsMenu.new(game, opts)
+  opts = opts or {}
   local rows = buildRows(game)
   local hooked = Runtime.call("ui.options.rows", sameRows, game, rows)
   if type(hooked) == "table" then
@@ -337,8 +338,8 @@ function OptionsMenu.new(game)
     Logger.error("ui.options.rows returned %s; keeping the vanilla rows",
                  type(hooked))
   end
-  return setmetatable({ game = game, rows = rows, index = 1, scroll = 0 },
-                      OptionsMenu)
+  return setmetatable({ game = game, rows = rows, index = 1, scroll = 0,
+                        onCancel = opts.onCancel }, OptionsMenu)
 end
 
 function OptionsMenu:update(dt)
@@ -361,9 +362,11 @@ function OptionsMenu:update(dt)
       changed = row.step(self.game, dir) and true or false
     elseif input:wasPressed("a") then -- CANCEL
       self.game.stack:pop()
+      if self.onCancel then self.onCancel() end
     end
   elseif input:wasPressed("b") or input:wasPressed("start") then
     self.game.stack:pop()
+    if self.onCancel then self.onCancel() end
   end
   if changed and self.game.writeOptions then
     self.game:writeOptions()
diff --git a/src/ui/PlayerPC.lua b/src/ui/PlayerPC.lua
index 1f11aebe..06a21f53 100644
--- a/src/ui/PlayerPC.lua
+++ b/src/ui/PlayerPC.lua
@@ -160,9 +160,12 @@ end
 function PlayerPC.new(game)
   game.save.pcItems = game.save.pcItems or {}
   return Menu.new(game, {
-    { label = "WITHDRAW ITEM", onSelect = function() withdraw(game) end },
-    { label = "DEPOSIT ITEM", onSelect = function() deposit(game) end },
-    { label = "TOSS ITEM", onSelect = function() toss(game) end },
+    -- keepOpen so B in the item lists returns here instead of dropping the
+    -- whole PC session (players_pc.asm re-shows the PC menu); same pattern
+    -- as BoxMenu's rows
+    { label = "WITHDRAW ITEM", keepOpen = true, onSelect = function() withdraw(game) end },
+    { label = "DEPOSIT ITEM", keepOpen = true, onSelect = function() deposit(game) end },
+    { label = "TOSS ITEM", keepOpen = true, onSelect = function() toss(game) end },
     { label = "LOG OFF" },
     -- silent PC session (BIT_NO_MENU_BUTTON_SOUND); players_pc.asm
     -- PlayersPCMenu TextBoxBorder (0,0) b=8 c=14 → 16x10
diff --git a/src/ui/PokedexMenu.lua b/src/ui/PokedexMenu.lua
index b5bceb2d..7902c93c 100644
--- a/src/ui/PokedexMenu.lua
+++ b/src/ui/PokedexMenu.lua
@@ -9,7 +9,8 @@ function PokedexMenu:sgbPalettes(game)
   return require("src.render.PaletteFX").wholeNamed(game.data, "BROWNMON")
 end
 
-function PokedexMenu.new(game)
+function PokedexMenu.new(game, opts)
+  opts = opts or {}
   local dex = game.save.pokedex or { seen = {}, owned = {} }
   local byDex = {}
   for species, def in pairs(game.data.pokemon) do
@@ -47,6 +48,7 @@ function PokedexMenu.new(game)
   local list = ListMenu.new(game, "POKéDEX", items, {
     footer = ("SEEN %d  OWNED %d"):format(seen, owned),
     pageJump = true, -- Left/Right page jumps like the original
+    onCancel = opts.onCancel, -- B returns to the start menu when opened from it
     onChoose = function(item)
       if not item.value then return end
       -- the DATA / CRY / AREA / QUIT choice (engine/menus/pokedex.asm
diff --git a/src/ui/StartMenu.lua b/src/ui/StartMenu.lua
index aa1cc93a..7a0db47a 100644
--- a/src/ui/StartMenu.lua
+++ b/src/ui/StartMenu.lua
@@ -19,10 +19,15 @@ function StartMenu.new(game)
   local flags = game.save.flags or {}
   local items = {}
 
+  -- vanilla start submenus return here on B (RedisplayStartMenu): the
+  -- generic Menu pops the start menu when a row is selected, so each
+  -- submenu gets an onCancel that re-opens it
+  local function reopen() Screens.push(game, "StartMenu") end
+
   -- POKéDEX: only after Oak hands it over
   if flags.EVENT_GOT_POKEDEX then
     table.insert(items, { label = "POKéDEX", onSelect = function()
-      Screens.push(game, "PokedexMenu")
+      Screens.push(game, "PokedexMenu", { onCancel = reopen })
     end })
   end
 
@@ -30,17 +35,17 @@ function StartMenu.new(game)
   -- an empty party; selecting it then just no-ops)
   table.insert(items, { label = "POKéMON", onSelect = function()
     if #game.save.party == 0 then return end
-    Screens.push(game, "PartyMenu")
+    Screens.push(game, "PartyMenu", { onCancel = reopen })
   end })
 
   table.insert(items, { label = "ITEM", onSelect = function()
-    Screens.push(game, "BagMenu")
+    Screens.push(game, "BagMenu", { onCancel = reopen })
   end })
 
   -- the player's name opens the trainer card (StartMenu_TrainerInfo)
   table.insert(items, { label = game.save.player.name or "RED",
     onSelect = function()
-      Screens.push(game, "TrainerCard")
+      Screens.push(game, "TrainerCard", { onCancel = reopen })
     end })
 
   -- SAVE shows the player/badges/dex/time panel then asks to confirm
@@ -74,7 +79,7 @@ function StartMenu.new(game)
   end })
 
   table.insert(items, { label = "OPTION", onSelect = function()
-    Screens.push(game, "OptionsMenu")
+    Screens.push(game, "OptionsMenu", { onCancel = reopen })
   end })
 
   -- LINK needs a party
diff --git a/src/ui/TrainerCard.lua b/src/ui/TrainerCard.lua
index 7493d2c5..0ef3d33b 100644
--- a/src/ui/TrainerCard.lua
+++ b/src/ui/TrainerCard.lua
@@ -30,8 +30,10 @@ local function quads16(img, count, stride, x0, y0)
   return q
 end
 
-function TrainerCard.new(game)
-  local self = setmetatable({ game = game }, TrainerCard)
+function TrainerCard.new(game, opts)
+  opts = opts or {}
+  local self = setmetatable({ game = game, onCancel = opts.onCancel },
+                            TrainerCard)
   local img = tryImage("assets/generated/trainer_card/badges.png")
   if img then
     -- badges.2bpp is 8 stacked [face, badge] pairs (DrawBadges FaceBadgeTiles)
@@ -66,8 +68,12 @@ end
 
 function TrainerCard:update(dt)
   local input = self.game.input
+  -- either button dismisses the card back to the start menu
+  -- (StartMenu_TrainerInfo: WaitForTextScrollButtonPress then
+  -- RedisplayStartMenu)
   if input:wasPressed("a") or input:wasPressed("b") then
     self.game.stack:pop()
+    if self.onCancel then self.onCancel() end
   end
 end
 
diff --git a/tests/mod_ui_tests.lua b/tests/mod_ui_tests.lua
index 4b079f2d..4199e79b 100644
--- a/tests/mod_ui_tests.lua
+++ b/tests/mod_ui_tests.lua
@@ -185,6 +185,83 @@ check(#menu.items == #VANILLA_START and menu.items[3].label == "ITEM",
 check(logged("ui.start_menu.items returned"), "the degrade is logged")
 hooks:removeOwner("bad")
 
+-- ------- issue #270: B in a start submenu returns to the start menu
+-- (RedisplayStartMenu), not to the overworld.  The generic Menu pops the
+-- start menu when a row is selected, so every vanilla submenu must carry
+-- an onCancel that re-opens it.
+local function gameForSubmenus()
+  local game = startGame()
+  game.save.inventory = {}
+  game.save.money = 0
+  game.save.pcItems = { POTION = 1 }
+  game.data.items = { POTION = { name = "POTION" } }
+  game.data.pokemon = {}
+  game.data.constants = {}
+  game.data.rulesets = {}
+  game.modStatus = { available = {} }
+  return game
+end
+
+local MenuClass = require("src.ui.Menu")
+for _, rowLabel in ipairs({ "POKéDEX", "POKéMON", "ITEM", "RED", "OPTION" }) do
+  local game = gameForSubmenus()
+  local start = Screens.push(game, "StartMenu")
+  for i, item in ipairs(start.items) do
+    if item.label == rowLabel then start.index = i end
+  end
+  press(start, "a")
+  local sub = game.stack:top()
+  check(sub ~= start, rowLabel .. " opens a submenu over the overworld")
+  press(sub, "b")
+  local top = game.stack:top()
+  check(top ~= nil and top ~= sub and getmetatable(top) == MenuClass
+    and top.items[1].label == "POKéDEX",
+    "B from " .. rowLabel .. " re-opens the start menu")
+  check(#game.stack.states == 1,
+    "B from " .. rowLabel .. " leaves exactly the start menu on the stack")
+  check(top.index == start.index,
+    "the re-opened start menu restores the " .. rowLabel .. " cursor row")
+end
+
+-- the trainer card also dismisses on A, back to the start menu
+local cardGame = gameForSubmenus()
+local cardStart = Screens.push(cardGame, "StartMenu")
+for i, item in ipairs(cardStart.items) do
+  if item.label == "RED" then cardStart.index = i end
+end
+press(cardStart, "a")
+press(cardGame.stack:top(), "a")
+check(getmetatable(cardGame.stack:top()) == MenuClass
+  and cardGame.stack:top().items[1].label == "POKéDEX",
+  "A on the trainer card also returns to the start menu")
+
+-- the options CANCEL row takes the same path as B
+local optCancelGame = gameForSubmenus()
+local optStart = Screens.push(optCancelGame, "StartMenu")
+for i, item in ipairs(optStart.items) do
+  if item.label == "OPTION" then optStart.index = i end
+end
+press(optStart, "a")
+local optMenu = optCancelGame.stack:top()
+optMenu.index = #optMenu.rows + 1 -- CANCEL
+press(optMenu, "a")
+check(getmetatable(optCancelGame.stack:top()) == MenuClass
+  and optCancelGame.stack:top().items[1].label == "POKéDEX",
+  "the options CANCEL row returns to the start menu")
+
+-- the PC session (players_pc.asm): B in an item list returns to the PC's
+-- root menu, which stays on the stack via keepOpen rows
+local pcGame = gameForSubmenus()
+local pcRoot = Screens.push(pcGame, "PlayerPC")
+press(pcRoot, "a") -- WITHDRAW ITEM
+check(#pcGame.stack.states == 2,
+  "WITHDRAW ITEM keeps the PC root menu underneath")
+press(pcGame.stack:top(), "b")
+check(pcGame.stack:top() == pcRoot,
+  "B in the withdraw list returns to the PC root menu")
+press(pcRoot, "b")
+check(#pcGame.stack.states == 0, "B on the PC root logs off to the overworld")
+
 -- ------- ui.options.rows and the descriptor refactor
 local OptionsMenu = require("src.ui.OptionsMenu")
 local function optGame()