School Days(1980)

Tomomi Takehara is the second of three sisters and an animation-loving junior high student who has been friends with Busiko and Takubo since childhood. While visiting Eirin High School, they see Ogishima, the star striker of the soccer team, play, and they decide to take the Eirin High entrance exam together. All three manage to pass, but on the day of their junior high school graduation, Tomomi receives a confession of love from Takubo. However, Tomomi mistakenly took it as a joke, and Bushiro, who had been watching from the shadows, got angry with Tomomi. After entering Eirin High School, the three were separated into different classes. and both Bushiro and Takubo became estranged from Tomomi.



(Source: Wikipedia, translated)