Your life has always been pretty ordinary. That is, until a new girl joins your class and you inadvertently save her life while trying to help her in a fight. Declaring herself to be a modern-day ninja, she names you her new Master and vows to serve you to repay the debt she owes. Not only that, but soon her apprentice arrives to do the same. And just when you think you've got things under control, their rival decides the best way to prove her superiority is by serving you as well. From holding duels in the cafeteria to calling you Master in front of everyone, these three ninjas have thrown your life into chaos. How can you possibly make them stop? Then again… are you sure that's what you want?