Yuuto Kuroma, a 14-year-old with a serious case of chuunibyou, accidentally summons the ultimate Dragon King using a magic circle he had doodled purely on a whim... (Wait, seriously?) On top of that, due to certain circumstances, Yuuto ends up becoming friends with a lonely evil dragon girl who had been sealed away for 3000 years...! Now, the fate of the world is casually entrusted to one unsuspecting boy!