Coco, played by Chara, is dropped off at a mental asylum for young teenagers, where she’s met by a chorus of oddly enthusiastic staff who confiscate nearly everything she owns except a crow feather scarf she clings to tightly. Inside her room, she soon meets other patients, notably Tsumuji, played by Tadanobu Asano, and Satoru, played by Koichi Hashizume, who become friends during a shared art therapy session. While in his cell, Tsumuji experiences a vivid, troubling hallucination of his grade school teacher who molests him, a memory that shadows his interactions with the others.
One morning, after Coco steals black paint from the storeroom, the three boys scale the asylum walls and peer out at the road beyond. They explain that they’re simply exploring and won’t get in trouble if they stay within the lines of the walls. Coco follows them along the block and, drawn by curiosity, stops near a church to watch a hymn recital. A priest emerges and speaks with them about the nature of God; Tsumuji admits he’s unconvinced of God’s existence because prayers for the end of the world go unanswered, while Coco declares birth to be the world’s beginning and death its end, insisting that her parents are her God. The priest gives them a Bible, encouraging them to read it.
Tsumuji pores over the Bible and points to Genesis as evidence that God created the world, which deepens their fixation on the book’s apocalyptic visions. Back at the asylum, they’re restrained and sent to a punishment ward, lying strapped to beds. At night, a staff nurse rapes Tsumuji, who then hallucinates the teacher taunting and urinating on him.
The trio’s Bible study deepens into a shared belief about an impending apocalypse. They interpret the book’s publication date as a reference point and grow excited about the event, planning a picnic as they wait for it to begin. They stray beyond the church and into the city, drawing stares as they wander in broad daylight. In the chaos, they steal a gun from a pursuing police officer and mock a billboard for a sports drink.
In a residential area, Satoru reaches for a discarded trash bag and is horrified to discover a severed hand, then recoils and runs from his companions. When Coco and Tsumuji continue their walk, a sudden rainstorm triggers Tsumuji’s trauma; he confesses that years of abuse drove him to stab his teacher to death on a rainy day. Coco comforts him and reveals her own secret—she killed her identical twin Kiki in a game of who-is-fake. They share a brief, intimate moment before reaching an offshore beacon at sunset.
They open the picnic basket, find it empty, and pretend to eat. Tsumuji suggests that shooting the sun with the police officer’s gun might trigger the end of the world. He fires three shots into the sun, but nothing happens. Coco teases him for being a lousy shot, then takes the gun herself and shoots herself in the head, ending her world. The crow feathers from her scarf burst into the air as Tsumuji cradles her body, and the gun clicks harmlessly into the empty sky.
