A couple of weeks ago I posed an isolated question.
Here is the full picture:
The signs are indeed at Bicester North station in Oxfordshire.
Bicester is home to Bicester Village, a retail park stuffed full of designer shops. It seems very popular with Japanese visitors traveling out on Chiltern Railways' trains from London.
A fleet of mini-buses transport passengers between the station and the shops (for a fee) - It is safe to assume that it is those buses that the Japanese sign is alluding to.