The cousin and arranged fiance of Sachiko; in order that a trusted man inherit the Ogasawara company, their engagement was arranged, although Sachiko detests it and denies that he is her fiancé. (It is later revealed that Sachiko once loved him and had her feelings spurned, which resulted in her disdain.)
First introduced when he is given the role of the prince in Cinderella: the joint play put on by the Hanadera school and Lillian Jogakuen. He has prestige in the Hanadera school since he is president of the Student Council there. However, by the time Sachiko reaches her third year, Suguru has already graduated.
He is originally identified as gay but later in the novels it is implied and even Yumi thinks it that he might actually be bi. He only told Sachiko he was gay as it was easier than trying to explain to a then still young Sachiko why he couldn't love her romantically. He has a crush on Yumi's younger brother, Yuuki. He is often seen in the company of Yuuki, taking him along on trips and gatherings, doting on him much in the way that Sachiko dotes on Yumi.
He is very arrogant, and is especially disliked by Satou Sei, as both are often at loggerheads whenever they meet, bickering or making snide comments at one another. It appears that they both know of each other's sexuality.
Despite his coldness, Suguru does care deeply for Sachiko, going so far as to tell her that when they are married, she can have lovers on the outside since he will only be her husband in name only. Sachiko however finds this offensive, and comes to hate him for it, thinking him selfish. He tries to aggravate his younger cousin so that she will be more open and truthful about her feelings, rather than burying them inside.
He has taken a great liking to Yumi and becomes very protective of he even to the point of confronting Sachiko's father when because of a misunderstanding it was briefly thought her father did something inappropriate to Yumi. He notes that the younger girl has had a very profound effect on his cousin. He also at one point after a 2nd Amusement park trip with Sachiko and Yumi tells Yuki Jokingly that he and Yumi are now dating what Yuki then questions his sister on.
His engagement to Sachiko was ended when Sachiko with him there told her parents they wanted out of it. It then came out that the engagement was of Sachiko's own doing as when she was a young child she said she wanted to marry him so the arrangement was made. Her parents only continued on with it because they had thought the two were actually in love.
