Mousse is from the same Amazon tribe in China as Shampoo-- Joketsuzoku. Ever since he was a child, he has been hopelessly in love with Shampoo, who (very vocally and physically) does not return his affections. But that doesn't stop him from continuously professing his love to her-- even if she only returns his feelings with contempt and annoyance.
Having grown up as an Amazon, Mousse is also a talented martial artist. He is known as the master of hidden weapons, and is constantly hiding things up his sleeves during a fight, including (but not limited to) chains, daggers, claws, training potties, eggs-- really, just about anything you can imagine, Mousse has hidden in his robes.
But of course, he has a HUGE weakness: Mousse is extremely blind and must wear big thick glasses in order to see. Often, he is known for mistaking other people (or even inanimate objects) for someone else.
After his first defeat by Ranma, Mousse returned to China in order to train, and decides to go to Jusenkyo. However, when the Guide shows him the spring, Mousse--because of his horrible eyesight--ends up walking right into a pool! Now, he joins the ranks of the cursed, and when splashed with cold water, becomes a duck.
Mousse works for Cologne at the Nekohanten, and is something of a pushover... his mission is to defeat Ranma and take Shampoo as his wife. Until he's accomplished either of these goals, he will continue to stay faithfully by Shampoo's side.
For information on the love of Mousse's life, Shampoo, click here.