Kuboyasu in his previous school wore the typical delinquent clothes. He sported a pompadour hairstyle, and wore a modified school uniform with his pants looking more like an over-sized skirt. After moving to PK Academy, Kuboyasu changed his looks into more of a normal student like wearing glasses and dyeing his hair dark violet. In school, he wears the standard uniform of male students in PK Academy while in days off, he wears long sleeves; possibly to hide his scars which were first seen by Kaidou.
(Source: Saiki Kusuo no Psi Nan Wikia)