Hisao Nakai

Hisao Nakai is the protagonist of the visual novel Katawa Shoujo, a normal boy whose life changes after suffering a heart attack that forces him to transfer to Yamaku High School, a center for young people with disabilities, where he must learn to accept his arrhythmia and forge new friendships and romantic relationships through the player's decisions.

Hisao looks like your average teenager and is above average height. His most noticeable features are the scar on his chest from heart surgery, which isn't usually visible because he always wears something, and his hair. Hisao mentions that during middle school he was teased because some strands of his hair tend to stick out no matter how hard he brushed it down (and he still does), and that his mother wouldn't let him shave his head at such a young age.

Hisao is generally a good person with a big heart, though sometimes his good intentions can get him into trouble (for example, during Hanako's Route and at certain points in Rin's Route), and other times he has a serious tendency to make mistakes. He has trouble adapting to his classmates' physical limitations, and has even found himself staring at other students (despite mentally berating himself for it), though as he spends more time at Yamaku he gradually gets used to it.

Hisao is very skilled in science and also enjoys reading (partly because it was the only thing he could do while in the hospital). This becomes more apparent when Mutou suggests that Hisao join a science club. He's a math whiz and struggles with abstract and illogical concepts, hence his odd relationship with Rin. Hisao has trouble with history, as shown in Hanako's route, and with English, as shown in Lilly's route. In Shizune's route, it's believed that he most likely wants to work as a teacher at Yamaku after graduating from university.