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 Second Place". 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 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.
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. Both of them seems to understand each other to an extent but Kei remains distant towards Yahiro because Yahiro is constantly poke fun and get on Kei's nerves.
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.