A movie about a spoiled young boy struggling to accept his new infant sister, if the potential consequences are anything to go by then yes, this movie does contain the stuff of nightmares.
- Kun's jealousy-induced scowl as he reaches out for baby Mirai while she's napping, he only pulls her ears and cheeks but still...
- It doesn't help that he ends up disturbing Mirai, incurring his mother's fury.
- Kun hitting Mirai over the head with a toy bullet train can induce concerns in parents. Thankfully Mirai is only frightened from this, but imagine if Kun had hit her hard enough to cause some serious damage.
- Kun's mother briefly turning into the hag/witch from his favorite storybook when she gets really mad at him since he keeps referring to and imagining her as said character, the boy may be in the wrong but he still looks positively petrified.
- The extent of how realistically twisted and contorted Kun's face becomes whenever he is crying or screaming.
- Kun whenever he has a tantrum, he furiously draws the aforementioned hag, referring to his mum all the while and throws his toys and books all over the floor.
- The fact that Human Yukko has a detachable tail that turns whoever it is attached to into a human/dog hybrid is a bit disturbing, even if Kun gets a lot of fun out of it.
- We don't see it but the extent of the trouble Kun's mother as a child ends up in after she and Kun make a complete mess of her home is so severe that Kun's grandmother has a conniption over it and threatens to throw away her daughter's toys. At hearing this little drama unfold, Kun is forced to run away with his face screwed-up and his hands over his ears.
- Kun seeing a live aircraft engine baring down on him at the beginning of his encounter with his great-grandfather.
- The Tokyo Train Station scene is the definition of nightmare fuel for the following reasons.
- Kun finds himself lost and alone with no sign of his family and he can't locate them because he doesn't know his parents' names.
- He sees a row of people resembling his mother, most of them have wide, vacant eyes and the one in the middle turns out to be the hag/witch.
- The robotic Lost and Found attendant and his tiny stopwatch-headed assistant are straight out of the Uncanny Valley.
- The Lonely Train takes on the appearance of a dragon with glowing teeth and eyes and inside, it is all luminous red with a disembodied voice giving Kun permission to board and an eerie aqua-blue mist that tries to pull him in and the seats resemble skeletons. Poor Kun can only scream and struggle as he is dragged onto said train.
- After struggling free, a petrified Kun briefly goes through a Heroic BSoD and only comes out of it when he sees the Lonely Train try to take Baby Mirai away.
- Future Mirai's hand reaching towards Kun, sure she may be rescuing him after he saved baby Mirai from the Lonely Train but after all he's just been through, it's still a bit unsettling.
- What is more, Future Mirai claims she's been looking for Kun and since he's just rescued her infant self, could it be possible that baby Mirai wandered away from her parents to look for her brother?
- Kun and Future Mirai witnessing the memory of Kun's deceased great-grandfather screaming in agony as he tries to swim away from the burning wreckage of his sinking ship and the corpses of his comrades with bloodied-up legs.
- At one point, Future Mirai soberly points out that if their great-grandfather had been even the tiniest bit unlucky on that day, neither of them would've been born...
