Yotaro 8-10 Dark blue Blond in the manga, brown in the anime Vol. 14 (Japanese) Episode 75 "Step Outside!" None None Onna-Ranma

Yotaro is a young and frail boy who is unable to go outside, despite his mother's attempts and trying to do so. Sickly and easily tired, Yotaro stays in bed all day and refuses to do any activity whatsoever - though he does have a wish. This wish is to have a panda of his very own, and one day, Yotaro gets his wish as none other than a wandering Genma (in panda form) is found by Yotaro's mother and taken home. At first, Genma is hesitant, but when he discovers how well he is treated (especially when it comes to food) he decides to stay in panda form and lounge around the household.

A worried Ranma eventually finds Genma lounging around at the house and, in female form, makes his way inside where she is disgusted by Genma (and Yotaro's) laziness. At first, Ranma tries to take Genma back by force, but ends up having to resort to subtler means to do so by trying to tempt Yotaro to go outside. It is during this time that Ranma finds out that Yotaro isn't sickly, he is rather very lazy and unwilling to go outside - and it is only when Ranma forcibly kidnaps Genma-panda from the house that Yotaro goes outside, chasing Ranma all the day back to the Tendo dojo.

Yotaro seems sickly at first, but it eventually is realized that his sickness is just a ruse to cover up for his laziness and reluctance to go outside. However, he is a very energetic boy and isn't really willing to give up what he has so easily.

(animeinfo.org)