In the final pages of the manga, Chiyo, with dead, hollow eyes, looks at Kiyoshi and says the last line of the series:

To decide the final victor, a tie-breaker "Wet T-Shirt Contest" is held. Kiyoshi, forced by Hana, pretends to have installed cameras to peep on the contest. Chiyo is heartbroken, believing he is a peeping tom.

Chiyo, realizing Kiyoshi is completely innocent, is overjoyed. She rushes to confess her love to him, believing her pure hero has returned. This is where Chiyo's story becomes one of the most controversial and darkly comedic endings in manga.

She walks away, her innocence shattered forever. The pure angel of Prison School is broken by the very perversion she tried to ignore. Chiyo Kurihara’s story is a dark satire of the "innocent pure girl" trope in anime. She starts as the only sane, kind person in a world of sadists and perverts. Her journey is not one of growth, but of destruction . She is punished by the narrative for her naivety. The world of Prison School cannot accommodate true innocence—it either corrupts it or destroys it. Chiyo’s ending is the final punchline: the one person who believed in pure love ends up completely unable to understand love at all.

Chiyo watches in stunned, silent horror. Her entire worldview collapses. The boy she loved as a pure, innocent hero is now on his knees with another girl's underwear in his mouth. She cannot process this.