Guess Who? (S04E06)

A high school student is visiting an amusement park with an older member of her club, whom she has a crush on. She's thrilled at the prospect of going on this date with the senpai she admires. But on the way home, they see a creepy woman on the train platform, and from that point onward, the girl's head is overtaken by a frightening suspicion... (Crunchyroll)