BEWARE OF SPOILERS
At first we meet Kuramochi when Eijun moves in his dorm, in fact, they share the same room together with Masuko-san. We soon find out what kind of personality he has: outgoing, a bad boy that enjoys to make fun of his kohai (mostly with Eijun, beating him up with wrestling moves when he can), he has always a sinister
and sexy smile on his face, he's a directed person who just says what he thinks without hesitation. At the same time, he's very polite with his senpai, especially with Kominato Ryosuke who is the teammate with whom he collaborate the most. Though from my description he can resemble only a really bad boy (poor Yoichi-kun...), the truth is that he has a very strong will and a huge sense of responsability towards everyone. He has an eagle eye and usually he catches every little thing that happen, good or bad. His words are generally harsh, but every time he says something, he does it using his brain and his heart, in order to do the best he can for his comrades.
Kuramochi's best ability is the speed. He's the fastest of the team and this makes him one of the best shortstops among all the teams (he was compared to Inashiro's Carlos for his abilities). Together with Ryosuke he's kinda the best match, they achieve almost every goal they want and seem unstoppable. He's the kind of person that in a match would make possible the impossible with everything he can.
Once they lost the final against Inashiro, match that would lead them to Koshien, it will be formed a new team and he will become the vice-captain (though I really think he had the impression that Kataoka kantoku wanted to ask him to be the captain). He will always support both Miyuki and Zono (that is vice-captain as him) with a greater determination. His new partner will be Kominato Haruichi, with whom he will try to build a good relationship (well, he's not 100% satisfied, but they're still working on it and their game grows always better).
His past is not one of the best, since he spent his years as a middle school student with a group of delinquents. His real goal was to continue to play baseball, but because of his status, any school asked him to enrol there up to the moment in which Takashima Rei, finding out the gift he had, proposed him to join Seido High. Kuramochi, at the begin, was a bit astonished, but at the same time, happy to see that at the end he could continue to play baseball. In the moment he went to tell everything to his companions, he unexpectedly listened to a conversation among them all where they were talking behind his back. The boy, disappointed, told them that he was going to Tokyo and so, he left. Once arrived in his new team, he started his new life and thanks to his senpai's advices and his companions, he became the person that he's at the moment~ I forgot to mention that he had wonderful blonde hair when he was a cute delinquent. ♥ (If you want to read this chapter, it is a special one called "Outrun", included in the Comic Guidebook too~)