How to Save the World by Sadame Tsukiyoda

Tsukiyoda Sadame, a hypocrite and a high-schooler who dreams of conquering the world. A person who's popular the moment he transfers into his new school. But suddenly a terrible truth is revealed to him! That there are these awfully ridiculous missions that he has to clear. And if he doesn't manage to clear them... the world will end?! Is this the work of God, or the Devil's deed? Your pride, honour, and appearances - cast it all aside and save the world, Tsukiyoda Sadame!