Based on the third Hamtaro game (fourth in Japan), Prince Bo falls from the sky when the rainbow disappears. Now Hamtaro and the Ham-Hams must help him bring back the rainbow. (Source: Wikipedia)
Genres: Adventure, Comedy, Fantasy
Watch Tottoko Hamtaro OVA 3: Hamuchanzu to Niji no Kuni no Oujisama - Sekai de Ichiban no Takaramono episode 1 online — subbed and dubbed, with automatic AniList / MyAnimeList progress sync.