Ranma 1/2

(from ebookjapan):

Soun was disappointed to find that Ranma was a girl. However, when Ranma got out of the bath, he turned into a boy and the panda turned into Ranma's father, Genma. The two had fallen into a fountain during their training in China, a fountain that turned them into a woman and panda respectively when they touched the water.

The Tendo family is initially in turmoil, including Akane, who has become a prospective bride, as they face the troublesome duo who go back and forth between man and woman, human and panda, although they can be restored to their original state if they are bathed in hot water.

This is the first volume of a new edition of the popular manga.