Son of the British noble Seigi Chōujin, Robin Mask. Dealing with a strict lifestyle from his father consisting of non-stop training of studying and exercising. As a result of this, Kevin ran away from the lifestyle he despised when he was 8 and soon, joined the d.M.p. and trained in the league as an Akugyō Chōjin (Evil Superhuman). This was also where he met his ally and adversary, Scarface, as his training partner.
After seeing the defeat of Tel-Tel Boy and MAXman from Mantaro however, he immediately left and became a lone wolf; siding with neither light nor darkness (though still assisting Seigi Chōujins when in need - mainly Mantaro his rival). He has a deep sense of honor that is rarely shown.
In the later part of the series, He does enter in the Chōujin Olympics: The Resurrection, assisted by his manager Croe (Whom is actually Warsman in disguise) and helps Kevin train for the event. Kevin does defeat all of his opponents he faced in the competition up to the main event with his main adversary, Mantaro Kinniku. In the anime version, he loses to Mantaro but where as in the manga, he wins it in an epic match.
Starting from his days in the d.M.p, Kevin has a Spider-Web Nest Tattoo on his back; Having images of Chōujins he has defeated. He still continues this practice even after his departure. He does have his own version of the Kinniku clan's Kajiba no Kuso Djikara (Burning Inner Strength) called Maelstrom Power. He has also won 1st place twice in the popularity contests in the manga.