Onbusuman Arc

This is the eighth story arc of Dandadan and the eighth within the Kintama Hunt Saga, drawn from Volume 15 and chapters one hundred twenty-one through one hundred twenty-eight. It formally introduces Rin Sawaki and plants the disguised antagonist Sanjome inside the school.

To search for Okarun's second missing ball without drawing attention, the group founds a History and Culture Research Club and ends up with a strange advisor named Sanjome, a deputy head teacher few staff can quite remember. He is secretly Saint-Germain, who arrived through the Gates of Hell and brainwashed his way into the post. Soon after, Rin Sawaki reveals she once recognized Okarun's Turbo Granny form and had handed his golden ball to a police box as lost property, only for it to already be claimed.

As they investigate, an intangible yokai pins Rin to the ground. Seiko identifies it as an Onbusuman, the spirit of a child that crushes its host under growing weight unless given love. Rin's story spills out: a falling-out with her aspiring-idol friend Mai Kawabanga, who died in a car crash on her way to collect Rin. To free her, Seiko stages an operation, hiring the Hayashi and float pullers to ferry the group toward the accident site while school spirits attack. Rin, urged to channel her bottled grief, finally sings again and restores the protective barrier.

At the accident site the Onbusuman recovers its memories and reverts to Mai's spirit. The two girls reconcile and sing a duet that shatters the animated school building. Mai chooses to linger as Rin's guardian spirit rather than depart, later granting her gravitational powers and acting as her microphone. Rin's singing voice becomes the foundation of her future ability, and the club gains the clubroom that will anchor coming arcs.