Manga artist Haruta Mahoro has a secret: she has been drawing her own work based on the setting of a manga left behind by her senior in high school, Yukishima Shu. One night, something strange happens to Mahoro, who has a strong desire to "return" Yukishima's work to him, who died 10 years ago. Mahoro travels back in time to her high school days, and with regret in her heart, she begins to live as a high school student again. However, in the past world, "a certain truth" about Yukishima's death is discovered, and the mystery deepens. (Source: Japanese = natalie.mu || Translation = MyDramaList) ~~ Adapted from the manga series "Sekai de Ichiban Hayai Haru" (世界で一番早い春) by Kawabata Shiki (川端志季).