Chiikawa gets lured to a mystery island by promises of easy rewards and exclusive snacks, which is exactly how these three operate: completely, catastrophically unprepared for whatever actually happens. The comedy lives in the gap between what they expect (simple quests, rare food) and what they actually encounter. By the time they realize the island has its own logic, you're already laughing at how perfectly their greed and naivety lined them up for disaster.

Chiikawa and Hachiware are relaxing in the square when Usagi turns up with a flyer stuck to its face. The flyer turns out to be an invitation to a special island, promising huge rewards for easy quests along with limited island ramen and sweets that cost next to nothing. Tempted, the group sets off on the trip, sailing over with Rakko, who doubts the flyer's claims. Once they land, something is waiting for them. The comedic slice-of-life film adapts the Siren Arc, a run of Chiikawa comics that Nagano posted on X during 2023.