Geekrown

Six candidates are vying for the throne of Nation A—but one is a traitor. This spy from Nation B must be found, or else Nation A will be taken over entirely. To protect her homeland's future, the princess has tasked Kai Blackman, one of the candidates, with tracking down the spy. The only problem: He's a frail, scrawny anime nerd with zero combat ability whatsoever. He does have on special skill, though: he can see through people's lies! Can this utter geek survive in this intrigue-laden battle for the throne?!

(Source: Kodansha)