Kei is one of the main protagonists in the series. He is ranked 1st
in the entire school which is why he has the habit of calling Hikari
"Miss Rank 2". He is the son of the CEO of Takishima Corporation, making him next in line for the company. He is Hikari Hanazono's undefeated rival. Kei becomes Hikari's boyfriend and they become engaged later on, making Hikari his fiancée.
Kei has messily styled light brown hair that tends to hang in his face and calm brown eyes. As he is in the S.A program, he wears the standard S.A uniform: a white blazer with the S.A. logo near the pocket, pale blue shirt, black tie, and dark blue pants. During the warmer seasons, he, along with the other male S.A. members, wears a short sleeved white shirt with the S.A. logo on the sleeve and near the pocket, green striped tie, and green pants.
Whenever he is challenged to a physical contest by Hikari he usually changes to a plain blue t-shirt and a pair of white pants.
When he's not wearing his uniform, Kei's dress style is athletic and modern.
At formal events, he wears a navy blue suit with a gray waist vest and light purple tie. When challenged to a physical event, he tends to rip off his tie.
Kei loves Hikari and is willing to do anything for her. He always tries to please Hikari in every way. At first, Hikari considered Kei as an arch rival/enemy, but it is seen that Kei has feelings for Hikari, which she fails to realize most times, making Kei irritated and confused. Despite this, Kei puts up with Hikari, knowing that he could never really be mad at her. For example, in episode 3, Kei ate Hikari's riceballs even though they were barely edible. In episode 22, Hikari kisses Kei on the forehead which shocks him but he says that he accepts her feelings for him. They've been together since childhood. Initially, Hikari proposes their engagement. In the final chapter, Kei proposes to Hikari with fireworks, though Hikari stated that if she didn't accept, he wouldn't win. She says that she will marry him the day she beats him. Hikari and Kei are seen as a future couple.
Akira is Kei's childhood friend, just like Hikari. They have a close but often provoking relationship. Typically, Akira takes Hikari away from him when he gets too close to her or he tries something weird on Hikari. In one of Akira's flashbacks, Akira states that Kei had an aura around him that said "don't approach me." Because Akira gets sick and tired of having Kei always win, she sets out to finally make Kei lose like the time by giving him a handicap and setting traps during the challenge, although Kei still managed to come out on top.
Yahiro is another one of Kei's childhood friends. Kei, along with Yahiro and Akira were all childhood friends when they were young because of their parents' jobs, although Yahiro wasn't as close to Kei as he was with Akira.
Aoi admires Kei despite being 3 years older than him. Kei and Aoi both have photographic memories and are "different" from others. Upon meeting Kei, Aoi dislikes his talent, but Kei tells him that they are "special." Since they are alike, Aoi eventually looks up to Kei and calls him "Master Kei." Aoi, along with Hikari, is part of the "After-School Takishima Club", a club of Kei's fans, although this is only featured in the manga.