普通の高校生として暮らしていた明光院景都ことゲイツは、柔道でメダルを取るために練習に励んでいたが、大会の試合中に再起不能の怪我を負い、選手生命を絶たれてしまう。
そこへウォズと名乗る青年が現れ、ゲイツに「君を魔王を倒す救世主に導くためにやってきた。そうでないと、常磐ソウゴが最低最悪の魔王として、その名を轟かせる」と告げ、ライドウォッチとジクウドライバーを差し出す。
It's September of 2018, and a group of high school students are more than ever excited to pursue their dreams. Sougo Tokiwa wants to become a desirable king, and Keito Myokoin (alternatively called by his friends as Geiz) works tirelessly to become the true judo champion while trying to impress his crush, Alpina Tsukuyomi.
However, one day Geiz suffers a career-ending injury during a judo match in a judo tournament, forcing him to give up his dream of become a judo champion. While still grieving, he was met by a mysterious man, who wanted to give Geiz a Ridewatch and a driver.
"My name is Woz, I came here to guide you to become a savior. If not, Sougo Tokiwa will become the worst and evillest demon king."
Meanwhile, a new transfer student leads him to nothing but one grand conspiracy.
