On the surface, Shū is instantly recognized as a "happy-go-lucky" type of person. He is approachable, silly, mischievous, brightly cheerful, and almost always smiling or grinning. His antics label him as the class jokester and, oftentimes, a source of regular comic relief. He expresses an obsession with cute girls and has been described as a skirt-chaser on multiple occasions. Shu is actually popular among the girls in his school, and unlike Raku, he receives love chocolates on Valentine's Day as well as a face-to-face confession from an admirer. Shū also has a habit of meddling in other people's affairs, especially Raku's and Chitoge's fake relationship; he often tags alongside Raku and the gang in various events despite being uninvited. But even so, Shu has a healthy relationship with the girls crushing on his best-friend Raku. Beneath the surface, Shū is actually intelligent and perceptive, often using his persona of humor to elevate this intelligence from discovery. He is very observant; he was almost immediately able to deduct the unauthentic nature of Raku's and Chitoge's "relationship" and Kosaki's crush on Raku. 

I don't have a set voice for him, but please he is a teen, so make him have a medium-pitched voice.