Because track No. 1, on the entrance side, is used by trains that pass the station without stopping, passing trains and trains that don't meet other trains coming from the opposite direction at the station use Platform 1, regardless of whether they're inbound or outbound lines.
駅入口寄りの1番のりば側が一線スルーとなっているため、通過列車及び行違いを行わない停車列車は上下線とも1番のりばを通る。