The Maomolin Bell is a pair of bells, one small and one large, which are used by the ghost cat Maomolin in order for him to attract a potential bride.
Initially the two bells appear to just be like those typically placed on a cat's collar, albeit with the larger bell being far too large for most people to carry let alone a cat. According to Shampoo, the bells are meant to be shared between a couple as a way to ensure that they stay together, however, Maomolin - who resides in the larger bell - later corrects this by revealing the bells are meant to bring him a bride.
Once awakened, Maomolin instantly falls in love with the female holder of the smaller bell and tries everything he can to convince the holder to agree to be his bride. Maomolin is also able to retreat inside the larger bell, where he is able to make it float etc.
After going on a visit to China, Shampoo returns to Furinkan with the bells which she bought in the hope that it would secure her relationship with Ranma. Despite initially refusing, Ranma gives in to Shampoo's request when she tortures him with her cursed form.
Later that same evening, Maomolin emerges from the bell and demands that Akane become her bride, terrifying Akane in the process. Eventually Ranma the other Dojo residents learn about Maomolin possessing the bell and his search for the owner of the smaller bell (currently in Shampoo's possession) so that she can become his bride.
Due to Kasumi ordering a late night takeout for everyone, Maomolin learns of Shampoo being the current holder of the smaller bell. However, Shampoo refuses Maomolin's proposal as she's already engaged to Ranma which forces Maomolin to declare that he'll defeat Ranma so that nothing stands between him and Shampoo.
When Maomolin returns the next evening, he continues his unsuccessful attempts at defeating Ranma until Ranma insults Shampoo, causing her to give Ranma the small bell to him before pushing him into the Koi pond and turn him into his female form. Seeing the female Ranma in possession of the small bell, Maomolin immediately jumps towards her, declaring Ranma his new bride. Unfortunately for Maomolin, Ranma's Nekoken soon sets in and she promptly scares off Maomolin. After this, Maomolin somehow gets back possession of the smaller bell and tries offering it to several female Furinkan High School students in the hope one of them will eventually accept.