Nangoku Shounen Papuwa-kun (1992)

Papuwa-kun is a young boy living a quiet life with his dog, Chappy, on a small island located somewhere in South Pacific, when Shintarou, who is being pursued by gangsters, invades their happy existence.

Chappi takes Shintarou's precious Jewel, thereby making the two main characters lifelong rivals. Together they experience a series of bizarre adventures and situations.