21-year-old nurse Kana, heading home after a night shift, finds herself on a crowded rush-hour train when she spots a girl and instantly falls for her. The girl is exactly Kana's type. However, she notices something strange—the girl is being molested. Surprised yet acting on instinct, Kana intervenes to help, even shocking herself with her own boldness. The girl's name is Yū, a 19-year-old college student. For Kana, who had been searching for a new romance, this encounter becomes a turning point. The two grow close, and their feelings gradually blossom. A warm, pure story unfolds as the bond between the nurse and the female college student deepens.