Tanita is a small plasticine girl who sets off in an airplane to tour the world, but crash lands on a mysterious group of islands and must then find a way to get back home. She comes across the MEC ("Main Evil Creature") who is involved in a plot to capture all of the fish surrounding the islands and turn them into evil gadgets. Naturally she therefore decides to combat the MEC while on her journey.

Tanita: Plasticine Dream has been made with stop-motion claymation, and outwardly looks and plays quite similar to the claymation game The Neverhood. Going along with the strange setting, many of the game's puzzles have quite unusual solutions. There are also multiple mini-games, some of which are arcade-like.