Chitose Is in the Ramune Bottle, Vol. 2 (manga)

When Kenta Yamazaki, former shut-in and all-around loser, asks Saku Chitose to teach him how to become popular at school...Saku can't quite refuse. After all, he's the man who works magic and takes care of things--everybody's hero. Under his instruction, Kenta faces a head-to-toe transformation from the way he talks to his fashion choices. Will he finally start living the dream? Or is the life of a popular kid harder than he thought?