Submitted by Evan B
Pooper: Kun finally embraces being Mirai’s older brother, and they save each other from the train of the damned. As they return home, they time travel through the past to revisit the seminal moments in their family history that led up to Kun and Mirai’s births.
A rambunctious young boy named Kun (voiced by Moka Kamishiraishi) welcomes home his new baby sister named Mirai. On top of getting a new baby sister, Kun’s mother returns to working full time as his father begins adjusting to being their caretaker while doing some freelance architectural work. Feeling ignored by his parents and growing jealous of the attention Mirai gets, Kun throws numerous tantrums. His anger is primarily directed at his mother (who he calls a witch), although in his anger he also tells Mirai he hates her and often plays pranks on the baby. One day while in the yard, the family oak tree glows and Kun is transported to a fantasy land. Kun meets a mysterious man with a tail there and eventually deduces the man is the human manifestation of their family dog, Yukko. He learns that Yukko similarly felt spurned after Kun was born (before Kun, Yukko was the “prince” of the household) and mourns that the family only feeds him generic dog food. Later, Kun convinces the family to feed the dog organic food, and the dog shares meaningful looks with the boy.
Later, the tree transports Kun through time where he meets Mirai (voiced by Haru Kuroki) as a preteen girl. She asks for his help in putting away ceremonial dolls their mom set up in honor of Mirai’s birth. Legend says that for every day the dolls are left out too long, the honoree (Mirai) will be delayed from finding love for a whole year. Their father has clearly forgotten and their mom is at work. Kun, teenage Mirai, and the human version of Yukko sneak through the house and manage to put the dolls away without their dad noticing. Mirai asks if their mission helped Kun get more affection for her, but he responds that it didn’t.
Kun continues to travel through time. He gets to play with his mother when she was a child and learns that she was equally as unruly as he is. Through this experience, he learns a trick to get his mom’s attention (the same trick she used to get her mother’s attention). He later meets a man who had a leg injured in the war, but went on to be a mechanic and motorcycle enthusiast. Kun later learns (while perusing a photo album with his parents) that this man was his great grandfather. Thanks to that journey, Kun learns how to ride his own bike. Although Kun becomes more considerate through his journeys, he still gets jealous when his parents focus on Mirai.
One day, Kun has a major tantrum after his parents force him to wear pants he doesn’t like. He threatens to run away and is transported away by the tree to a train station. There, he meets a teenager (later revealed to be the teenage version of Kun himself) who tells Kun that he should focus more on embracing his family than on his own silly needs. Kun ignores the teenager and gets on a train to Tokyo. Although Kun is at first thrilled by the experience (as he is a big lover of trains), he soon realizes he is lost. A train employee tells Kun that he must board a train of the damned where all lost children go. On the platform, he sees his baby sister. Kun runs to save his sister from getting on the train, exclaiming that he wants to be her big brother and that he loves her. After saying this, the teenage Mirai appears and saves Kun. They fly through the air towards their home. To reach home, they must fly through their “family tree.” There, Kun watches moments from his family’s history – how his great grandmother purposefully lost a race to his great grandfather with the injured leg (the bet was that if he won the race, she would marry him), his father’s own struggles to ride a bike, Yukko himself leaving his mother to be adopted by the family – and end up back in their home. There, teenage Mirai and Kun tell young Kun that, this time, he transported to them (whereas in the past they had transported to him). They point out that he has now seen all the many miraculous moments and people that led up to the birth of he and Mirai ans without family, he would never exist.
Kun returns to the present and, without a fuss, puts on the pants his parents want him to wear. He then sees his little sister and lovingly embraces her, having accepted his role as her big brother.