Manga Seishun Re:try
Marking the end of one's youth--the high school graduation ceremony. Itsuki, the elder of the twins, spent the best graduation surrounded by friends and his girlfriend. Haruka, the younger of the twins, spent the worst graduation all alone. During the ceremony, the two accidentally fall from the roof--and find themselves back in time at the entrance ceremony. From there, the two's "retry" at youth begins.