Ryusei is a chuunibyou, plain and simple. He has an edgy personality, speaking strangely while being quite animated. He comes off as shameless and confident, but if you can manage to trip him up, the act drops.
Deep down, Ryusei can get easily embarrassed. His natural speech pattern is quite normal, and he can even get a little pouty if you prod him enough. He's also incredibly shy about love and his own feelings, avoiding that topic at all costs.
Ryusei is the older twin brother to Junsuke Nakazawa; but he has almost no memories of his little brother. Ryusei instead believes his only family is his mother, father, and two elder sisters. He vaguely recalls Jun, but also believes it's something he made up.
Ryusei begins to have premonitions of Ichigo; and vows to keep her out of danger. It makes this easy, as Ichigo has visions of Ryusei, thus the two working to keep the other safe.
Ichigo is constantly in danger, it would seem out of all the classmates, she's always in the most peril. Ryusei faithfully goes out of his way to save her; which eventually leads to feelings. They begin dating in early January.
Their happiness is cut short in mid-August, however. Ryusei envisions Ichigo being shot as they're walking, he takes a different path to avoid the shooter, but instead they run right into them. Instinctively, Ryusei puts himself between the shooter and Ichigo and is shot.
Ryusei is shocked when he learns Ichigo has an interest in the occult, which makes talking very easy. As their friendship grows, he begins to realize he's falling for the girl. Ichigo's honesty makes admitting his feelings easier, and they eventually begin to date.
These sweet boys bring out a side to each other that nobody ever sees. They ruffle each other's feathers, and are constantly fighting or teasing one another. It's out of love though! They can really be themselves together; even now, the two spend the night at each other's houses.
Another childhood friend, whose more like a sister to him. They constantly butt heads, much as siblings would. These two are spotted at the Drama Club together the most, though Ryusei is not an official member. This drives Aiko insane, as Ryusei has even played parts in plays.