A student who was being bullied for money until Sakamoto helped him get a part-time job at McDoodle's (WcDonalds in the anime). Kubota managed to stand up for himself in dealing with the bullies, and now hangs out with Sakamoto. Like Sakamoto, he has 'secret skills,' though they are all related to fast food.
He cares for his hair so much, that when Hayabusa's underclassmen shaves all of his hair until he goes bald, he cries and stays in his room, not wanting to see anyone. He is also seen bringing hair care equipment to school. Likewise with other students, Kubota joins them in a cream pie attack against Sakamoto before he moved to America.
Wikipedia