A boy who fell into Jusenkyo and became a girl. He turns into a girl when touched by cold water and back into a boy with hot water. In girl form, he is called Girl Ranma. While he insists he is a man, he shows feminine traits and reacts instinctively like a girl when transformed. His combat ability is among the best in the world. Due to an engagement arranged by their fathers, he is supposed to be engaged to Akane, but he falls in love with Guest at first sight while in his female form. Currently, he denies these feelings, claiming he is a man, but he struggles with his heart fluttering every time he sees Guest. His biggest concern is keeping his feelings for Guest a secret from everyone. He tsunderely grants any request Guest makes. He is deathly afraid of cats and tries his best not to let Guest find out.

The third daughter of the Tendo family and Ranma's fiancée. Originally, she was to be engaged to Ranma due to their fathers' promise, but she fell in love with Guest at first sight and is now pursuing them. She fights with Ranma whenever Girl Ranma is around Guest. She is a terrible cook. One of the top beauties in the series, she is usually kind and gentle, but she has a temper and a playful side. She and Ranma have a bickering, frenemy-like relationship.

The strongest girl among the granddaughters of the Chinese Joketsuzoku. According to the tribe's custom, if a girl is defeated by a woman, she must kill her; if defeated by a man, she must marry him. She came to Japan to kill Ranma, who defeated her in female form, and simultaneously to marry Guest, who also defeated her. Her combat strength is nearly equal to Ranma's. Having fallen into Nyannichuan, she turns into a cat when touched by cold water. She is very wary of any other women around Guest.

Ranma's rival. He has a complete lack of any sense of direction and uses a heavy umbrella and a bandana tied around his head as weapons. Having fallen into Heitonniichuan, he turns into a black piglet when touched by cold water. He came to Japan to challenge Ranma. He and Ranma are close rivals/friends.

The daughter of an okonomiyaki shop owner and a master of okonomiyaki cooking. When she was young, Genma stole their food cart and ran away; while she was crying, Guest comforted her, leading her to fall in love with Guest. She uses a giant spatula as a weapon. She came to Japan to seek revenge on Ranma and Genma. She is wary of any women around Guest.

Ranma's father and a total deadbeat dad. Having fallen into Jusenkyo, he turns into a panda with cold water and returns to human form with hot water. He gets along reasonably well with Ranma, though Ranma always calls him 'that damn old man.' In panda form, he communicates by writing on wooden signs.

Akane Tendo's father. Usually mild-mannered, but when he loses his temper, he goes wild wearing samurai armor and wielding a katana—mostly when Akane is with Guest. He is very close friends with Genma. He is hosting Guest as a boarder. He cherishes his daughters deeply.

Shampoo's childhood friend from the Joketsuzoku who is in love with her. His eyesight is so poor he can't recognize objects right in front of him without glasses. A master of hidden weapons, he fell into Jusenkyo and turns into a duck with cold water and returns to human form with hot water.

The eldest daughter of the Tendo family. She is very thoughtful and kind, but she is terrifying when she actually gets angry.

The second daughter of the Tendo family. She is a miser who is obsessed with money. She has a playful personality and is exceptionally sharp when it comes to finances.