Eiga Chiikawa: Ningyo no Shima no Himitsu

Chiikawa and Hachiware relaxing, when a rabbit with a flyer on its face suddenly appears. Hachiware looks at the flyer, which reads, "Invitation to a special island." Lured by tempting promises including great rewards for simple hunts on the island and essentially free sweet and spicy dishes such as limited-edition island ramen and sweets, Chiikawa and friends decide to go to the island. Suspicious with the flyer, Rakko goes with them to the island. What awaits them when they arrive on the island?