The board has been replaced with a sticker on which the characters are written horizontally, perhaps because a rectangular white 'bear' sign has been placed for the buses in which an air conditioner is installed (black characters on a yellow background are used for the sticker).
その後冷房車に長方形の「白熊標識」をつけるようになったためか、横書きのシールに変更された（シールは黄色地に黒文字）。