Four-year-old Kun struggles with jealousy after his newborn sister, Mirai, begins receiving most of his family’s attention. Retreating to the garden, he encounters Mirai as a teenager from the future and embarks on extraordinary journeys across his family’s past, gradually discovering new perspectives on love, belonging and what it means to become an older brother.
| Actor | Role |
|---|---|
 Moka KamishiraishiKun (voice) | Kun (voice) |
 Haru KurokiMirai (voice) | Mirai (voice) |
 Gen HoshinoFather (voice) | Father (voice) |
 Kumiko AsoMother (voice) | Mother (voice) |
 Mitsuo YoshiharaMysterious Man (voice) | Mysterious Man (voice) |
 Yoshiko MiyazakiGrandmother (voice) | Grandmother (voice) |
 Koji YakushoGrandfather (voice) | Grandfather (voice) |
 Masaharu FukuyamaYoung Man (voice) | Young Man (voice) |
 Kaede HondoBaby Mirai (voice) | Baby Mirai (voice) |
 Daniel Dae KimGreat-Grandfather (Young Man) (voice) | Great-Grandfather (Young Man) (voice) |