He comes from the main branch of a small, but renowned and wealthy family. Although he may not look like it, he is the eldest son.
Though all four of them study at the same prestigious university, the other three have been advancing together since kindergarten through the so-called internal escalator school system, and only Hirotsugu entered the university from the "outside", by applying from the high school division.
Perhaps for this reason, he gets grumpy every time the topic shifts to anything that happened before middle school. He's a semi-professional pianist, but rarely plays in front of others, and gets angry if you praise him.
He is dexterous and good at repairing machinery.
[Translated from
Official site and
Wikipedia]