Serpo Arc

This is the third story arc of Dandadan and the third within the Kintama Hunt Saga, covering chapters eighteen through twenty-seven and adapted across episodes eight to ten of Season 1. It expands the alien side of the setting and pushes the budding romance between Momo and Okarun while folding Aira into the core cast.

A private workout goes wrong when Aira tries to kiss Okarun and Momo walks in on the tangle, convinced she has been lied to. The rift is still raw when the Serpo strike, trapping the students inside a water-filled Empty Space and deploying a crab-like Mantisian to capture Okarun, whose yokai abilities have caught their interest. Aira awakens the powers of Acrobatic Silky and fights back, but it is Momo's arrival, cancelling out the aliens' psychokinesis, that turns the tide. The cryptid Nessie also surfaces in the flood.

As a last resort, a Serpo fuses with the crab alien and Nessie into the Serpo Dover Demon Nessie. Momo, Okarun, and Aira learn the hybrid cannot fire its water blasts continuously and that its mantis-shrimp arms tear apart out of water. Using Okarun as a living speedboat, they exploit those weaknesses and rip the fusion in half.

Okarun clears up the misunderstanding, and Aira publicly admits she spread the cruel rumor about Momo, costing herself her social standing. The defeated Mantisian, revealed to need money for his sick son's transfusions, is taken in and helped when Seiko discovers his blood is identical to milk and gifts him a cow. He becomes a recurring ally. The arc closes with the arrival of Jiji, Momo's childhood friend and first crush.