Sunao Fujimori

Sunao is Sora's childhood friend and current roommate. Easily angered, he isn't above punching anyone who makes him lose his temper, especially Sora. His name "Sunao" means 'straight-forward', which fits him to a tee. At first, he claims he hates Sora, but he becomes closer to Sora with each game/episode. Just as Sora calls Sunao by his last name, Sunao refers to Sora as "Hashiba" and in some episodes with the nickname "Kuu-chan." He has an alternate personality named Ran. They look very similar in the anime though a defining feature of Ran is his red eyes.

(Source: Wikipedia)