Hanasaki Mai works as a teller for a branch of Tokyo Daiichi Bank. Suddenly, she gets transferred to the Tokyo Daiichi Bank's headquarters office. Her job is to fix problems that arise at its various local branch offices. Hanasaki Mai has the type of personality where if she believes she is right, she cannot keep quiet about it or give up. At her new department, she sees many mistakes that take place inside the bank, which she never noticed before.