Hiroki has short, wavy black hair and wears glasses.
Hiroki is a laid-back, gentle person who is polite and kind to everyone, even his juniors, which is something that earned him the liking of everyone in the kyudo club. He tries to be helpful to everyone, such as pointing Ryouhei Yamanouchi to the archery supplies shop when he asks him about target panic.
Hiroki met Daigo in their first year of middle school. Daigo was the only one who actively talked to him. They became friends when they both joined the kyudo club. In high school, Hiroki was selected to become the dorm manager. Hiroki won the boys' individual competition at the High School Prefectural Tournament the year before.
Kirisaki High School Prefectural Tournament Selections Edit
Hiroki ended the selections with ten hits, guaranteeing him a spot on the Kirisaki Prefectural Tournament team.
He and the club's vice-president, Daigo Sase, invite the other members who are chosen for the team to dinner in a restaurant, but only the first-year students Shuu Fujiwara, Senichi Sugawara, and Manji Sugawara accept their invitation, as the second-years Kabashima and Yushima turned them down.
As they are eating, Daigo steals some food from Senichi's ordered dishes, causing him to complain to Hiroki. Hiroki lightly scolds Daigo for grabbing food with his hands. Daigo warns the twins about shooting too quickly, which can cause the people who go behind them to get angry. Hiroki reassures them that though they may be resented by the other club members because they are first years, he will back them all up, so they should all practice harder than ever. The twins energetically agreed with him. Hiroki then turns to Shu and praises him for his exceptional skill, saying that even he wants to follow his example. He asks him if he started to do kyudo in middle school. Shu corrects him and says he started doing it in fifth grade, after his father found a kyudo teacher who taught the Imperial Guards for him. These memories stirs up some conflicted feelings for Shu, which Hiroki does not notice, who is impressed and says that must be the reason why his shooting is so elegant and he is so skilled. Shu replies that is not the reason at all, and that the biggest reason for why he improves his skills is that there is someone who wants to shoot through his heart. 
Prefectural Tournament Preliminaries Edit
Hiroki arrives at the tournament venue with the rest of the Kirisaki team. The twins and eventually Shuu head off by themselves to go talk to Kazemai, and he and Daigo call them back, waving at them with idol clear file folders. For the boys' individual competition, he and Shuu tied with both of them getting kaichu, and Shuu won the subsequent izume competition, making him the winner.
For the team competition on the second day, Hiroki serves as the oomae. He shoots perfectly well, and ends the competition with a total of eight hits, a kaichu, along with Shuu. The Kirisaki team thus takes first place. 
Prefectural Tournament Finals Edit
Before their final tournament match against Kazemai, Hiroki gives his team a talk. He tells them that for he and Daigo, this will be their very last high school Prefectural Tournament. Sase takes over for him, saying that as the starting lineup, they are burdened with the pressure of hitting as well as the feelings of their fellow members who weren't chosen. He declares that Kirisaki is strong not because it is a powerhouse school, but because they are there. The five members bump fists. They then go line up next to Kazemai.
During the competition, Hiroki is the oomae and hit with all four of his arrows, but his team ends up losing. 
Despite their different temperaments, Hiroki and Daigo are close friends. Hiroki is the only one who can listen to Daigo talk on and on about idols with a calm smile on his face.