Suguru Kashiwagi is (spoiler: until he leaves Hanadera!!!) the student council president at Hanadera Academy. He is also both Sachiko Ogasawara's cousin and her betrothed through an arranged marriage. Although he's seen as being a bit on the arrogant and self-absorbed side, he's actually quite easy-going. He cares about his cousin, but doesn't seem all that interested in marrying her.
Suguru was betrothed to Sachiko Ogasawara as a child. Even though Sachiko harbored romantic feelings towards him, Suguru was not romantically interested in her due to the fact that he is gay. When Sachiko started high school, Suguru told her that he was a homosexual so if she wanted children she would have to take a lover outside of their marriage. The reason for their engagement mainly stemmed from the fact that Sachiko was the only child of the Ogasawara family. Her grandfather preferred to have a male take charge of the company but also wanted the heir to be part of the family. Suguru seemed to be the logical choice but Instead of just adopting Suguru into the Ogasawara family, Sachiko's grandfather engaged him to Sachiko. This way Sachiko would also be at the head of the family when the time came for Suguru to take over.
He is Sachiko's cousin and arranged fiancé, because in order that a trusted man inherit the company owned by the Ogasawaras, their engagement was arranged, although Sachiko detests it and denies that he is her fiancé. He is very arrogant, and especially disliked by Sei Satou, but he has prestige in Hanadera Boys' Academy since he is president of the Student Council there when the story begins. He is gay, and appears to have a crush on Yumi Fukuzawa's brother, Yuuki Fukuzawa. Despite his arrogance (and a fast car), he does somewhat cares about Sachiko and is glad she has Yumi as a good friend. He also serves as a representative for the Matsudairas, keeping a close eye on Touko Matsudaira. He also shows that he deeply cares for Tōko, displayed in the fourth season when, enraged by her bullies at their summer home, he put his car in Race Mode (he pushed the pedal fully down to the metal) as the traffic lights went green. He has a reputation for his horrible driving skills—many people have given this feedback after taking a ride in his car (such as Sachiko, the Fukuzawa siblings, and Youko Mizuno).
His engagement to Sachiko was easily ended by Sachiko when she told her parents she wanted out of it. It turns out the engagement was of Sachiko's own doing as when she was a kindergartner she said she desperately wanted to marry him at all cost so the arrangement was made. Sachiko did not remember this and did not know it was the real reason behind the engagement. When he and Sachiko told her parents they wanted out of it her parents treated it as no big deal and simply ended it as they had mistakenly been assuming the two was in love but now knew they weren't
. I'n Vol 25 it is implied that Suguru might not actually be just gay but is actually Bi. Even during the 2nd attempt of the amusement park trip Yumi thinks to herself that he might be bi. She wasn't sure which it was originally said he was as she tries to decide if he is flirting with her or not as they go to get on a roller coaster together again. He told Sachiko he was gay as it was simpler then trying to explain why he could not love her romantical whether she was a man or a woman to a then still immature Sachiko.
He is extremely protective of Sachiko and also becomes protective of Yumi becoming nearly violent towards the Mystery club members when he thought they had done something to her and then getting on the ground and begging her forgiveness for letting it happen. He also confronts Sachiko's father when through a misunderstanding it was thought her father had done something inappropriate to Yumi till the misunderstanding was cleared up.
After the 2nd amusement park trip he starts jokingly telling Yuki that he and Yumi are now dating. Yuki then proceeds to question Yumi if it was true.
Surugu is the cousin and fiancée of Sachiko and also the cousin of Touko Matsudaira. He is quite protective of both of them. Suguru enjoys toying around with Yumi's brother Yuki and nominates Yuki for student council president shortly before graduating. In the later books/ seasons we come to realize that Surugu cares deeply for Yumi although she views him as a rival for Sachiko.
- "He… Suguru-san, is not a bad person. But he acts only for himself, but he doesn't seem to realize it. He can't understand how other people feel, nor does he bother to even think about it. That's why if he hurts someone, he doesn't understand why, and he doesn't even think about whether he was the cause." ~ Sachiko Ogasawara (Light Novels Vol. 1)
- "Kashiwagi-san, that idiot, was talking with the college-aged Onee-sans around him, and his speech seemed to make the surrounding flowers bloom." ~ Yumi Fukuzawa's P.O.V. (Light Novels Vol. 21)
- "Then why did you tell Sachko-sama that?"
"That you're gay."
When Yumi Fukuzawa said those words, Kashiwagi-san's normally self-confident, youthful figure faltered for just a moment.
"... My god. Just how much do you know."
- "There's some parts of me that even you can't see." ~ Suguru [To Yumi Fukuzawa] (Light Novels Vol. 21)
- The name Suguru means "outstanding".
- Surguru's surname Kashiwagi specifically refers the Japanese Emperor Oak/Daimyo oak (Quercus dentata) (kashi) and "tree" (木) (ki or gi).