Kun, a young boy, feels neglected and jealous when his family brings home his newborn sister, Mirai. Struggling to adjust to the changes, Kun retreats to their garden, where he discovers a magical portal. Through this portal, he meets various family members from different points in time. An older version of Mirai guides him through these encounters, helping him understand his family history and the significance of their roles. Kun experiences these surreal adventures which teach him valuable life lessons about empathy and self-worth.

As Kun continues to explore through the portal, he meets his mother as a young girl and his great-grandfather as a young man. These vivid journeys start to reshape Kun’s perception of his world and help him come to terms with his new sibling. Along the way, he learns about bravery, love, and the importance of family bonds. Through each mystical encounter, Kun begins to overcome his initial feelings of jealousy and finds a deeper connection with his family, particularly with his younger sister, creating a heartwarming story about growth and familial love.