A girl who spent seventeen years being serious about everything gets reset to six, and suddenly the delinquent she was always criticizing becomes the only person who understands what she's actually lost. The show builds its comedy on a brutal premise: she's happier now, and everyone knows it, and nobody can say that out loud. Watching Nenji protect her secret while she forgets why she ever needed protecting becomes something sadder than any amnesia plot has the right to be.
Nanaka has always been the responsible one: straight-A student, clear ambitions, relentless in her criticism of Nenji, the perpetual troublemaker she somehow calls her best friend. That changes instantly when a bad fall down the stairs rewires something fundamental in her brain. She wakes up with the mind of a six-year-old trapped in a seventeen-year-old body, with no memory of the person she was becoming. Now Nenji and her father face an impossible situation: keep this secret while helping Nanaka navigate a world that expects her to act her age. School becomes a minefield. Simple conversations turn complicated. The girl who spent years judging Nenji's immaturity now sees the world through genuinely innocent eyes, and he's the one forced to protect her, guide her, keep up the charade that nothing is wrong. What emerges is both comedy and heartbreak. Watching Nanaka rediscover herself from scratch means confronting why she was so hard on everyone around her in the first place. Her journey becomes about learning to grow up differently this time.