Shuujin to Kamihikouki: Shounen Paradox  

Prisoner and Paperplane: Boy Paradox, 囚人と紙飛行機 少年パラドックス

The narrative begins on April 21st when a person known as Number 420 starts telling his story. He reveals that he was once imprisoned and had a negative outlook on life, believing in the concept of "happy ends." Despite this, Number 420's real name remains unknown, and everyone refers to him by his prisoner number, which is 420. Kaimural (Kaito) leads him to his cell, where he finds a blanket and ceramic walls. Two new characters are introduced: Rythm Garcha and Shazna Ivory. They attempt to harm Number 420 emotionally until he breaks down in tears.