Yoshiyuki Sakurai originates from the malfunctioning magical sakura tree on Hatsunejima island. He was created when Sakura Yoshino, burdened by prolonged loneliness, wished for a family; he embodies the son she and Jun'ichi Asakura never had, his name reflecting this origin through a fusion of elements from "Yoshino Sakura." Yoshiyuki resides with Sakura Yoshino, sharing a household with stepsisters Otome and Yume Asakura—Jun'ichi and Nemu's granddaughters—though they are not biologically related. As a second-year student at Kazami Academy, he exhibits a kind, gentle, and occasionally oblivious demeanor, unintentionally attracting romantic attention while navigating school life alongside friends like Koko Tsukishima, Wataru, and Suginami. His supernatural abilities include magically creating wagashi (Japanese sweets), inherited from Jun'ichi, and experiencing involuntary psychic visions of others' dreams or desires.

The core conflict emerges when the sakura tree begins indiscriminately granting impure wishes, causing widespread disruptions. This forces Otome to confront withering the tree to restore balance—an act that would simultaneously erase Yoshiyuki by revoking Sakura's original wish. Despite Sakura Yoshino fusing with the tree in a final stabilization effort, her failure leads Yoshiyuki to persuade Otome to prioritize the island's safety over his life. Consequently, he disappears following the tree's deactivation. His narrative concludes with an epilogue where he mysteriously returns, though Sakura does not; this return hints at his maintained connection to the tree's residual magic or the enduring promise to wear Sakura's protective pendant, suggesting a partial restoration of his existence. Expanded media like the *Plus Situation/Plus Communication* adaptations explore his interactions with supplementary characters such as Erika Murasaki and Akane Hanasaki, though these routes do not alter his fundamental origin or fate.