The player takes take control of Ruka-chan, an aggressive demon girl who lives in a world filled with harmful monsters. Much of her past is shrouded in mystery and her age is deliberately hidden in context. She lives a long life but has the mentality of a 13-year-old girl. This game had more fluidity and had better gameplay than the North American version. Compared to the futuristic setting of The Jetsons, the Japanese version uses a contemporary setting with Japanese architecture. Extra features were added into the Japanese version including an extra underwater level, a mini-game, and a training mode. People who don't care for the Japanese style of gaming would be better off with the North American (Jetsons) version of the game; even though it's harder and longer.
The character sprites used in the Jetsons version of the game are considered to be a similar style of animation to the Ruka-chan version.
Source: Wikipedia, "The Jetsons: Invasion of the Planet Pirates", available under the CC-BY-SA License.