Jisatsu suru ni wa Mukanai Kisetsu

Nagase sees his classmate, Tsubasa Amamiya, leap in front of a train one morning and becomes curious about her reasons. His friend Fukai gives him a capsule, calling it a small time machine. Nagase takes it and wakes up two weeks earlier. He encounters Amamiya on a rainy rooftop. The story is the first prize winner of Kodansha Ranobe Bunko's 6th Rookie of the Year award.