Nursing a long-unrequited love, sales manager Takafumi Yokozawa drinks alone and wakes up the next morning in the apartment of Zen Kirishima, an editor-in-chief, with no memory of the night before. Pressed into spending time around Kirishima and his young daughter Hiyori, Yokozawa slowly forms a paternal bond with the girl and finds his guarded heart shifting. This film spins a side story out of the BL series The World's Greatest First Love, centered on Yokozawa.