Mariko Nakamura is a friend of Suzy Mizuno as they both attend the same clubs together at Mochinoki Middle School and Suzy in the Japanese version calls her "Mari-chan".

Mariko, however, is seen to be more conceded and obsessed with her appearance than Suzume tends to be, her importance, along with Kiyo's other friends' importance's develops as the story progresses. She also has great cooking skills and is skilled in ping pong, even though Gash and Kiyomaro managed to beat her.

Takamine Kiyomaro, a depressed don't-care-about-the-world guy, was suddenly given a little demon named Gash Bell to take care of. Little does he know that Gash is embroiled into an intense fight to see who is the ruler of the demon world. All of the demons have to pick a master on Earth and duke it out with other demons until one survives. Needless to say, Kiyomaro becomes Gash's master, and through their many battles, Kiyomaro learns the importance of friendship and courage. 