This will be a quicker Yuri Quickie than usual as Nation members only need check out two episodes to get the gist.
The show as a whole is a bunch of shorts about people at the railroad crossing. During that time one or both people have a conversation or inner monologue about something, usually the person standing next to them. The curious can check out the other groups if they so wish though only one of them is Yuri. That being the star couple of the first episode and the last one. It is about an energetic senpai and her soft-spoken kouhai. The senpai wants to make the most of their youth and asks her kouhai to do something so memorable it encapsulates their youth leading to the two yelling out their crushes, if they had one, while the train passed. What happens next I leave readers to see for themselves.
PS: I sort of recommend episodes 2 and 11 for maximum thigh power.