Motoharu is a second-year high school student of Prefectural Sanada North High School and a member of its student council. He is in Class 2-A. Despite his "Yankee" moniker, Motoharu is never depicted doing delinquent acts. Instead, he is shown to be delicate and compliant. Still, he is also the one who tries to talk sense into his friends, and occasionally discourages their mischief.

He maintains a good relationship with his sister but this can be attributed to his lack of courage to go against her or her friends. He is also very skilled in a lot of things, like housework, but had to learn how to ride a bicycle from Yoshitake. He initially had his hair swept back but later let it down to hide the acne on his forehead.