Supplementary information. "OK牧場" was originally used by a professional boxer/an actor ガッツ石松 as the meaning of "OK". He took it from the Japanese title of a movie OK牧場の決斗 Gunfight at the O.K. Corral. "OK牧場博多駅前支店" is a variation of it, which seems to be initially used in a game you are referring to.