To save her younger brother, who was attending an all-boys school, from being bullied, her older sister, Mahiro, disguised herself as a man and snuck into the school, capturing the bullies' weakness. and can stop bullies. . However, Mahiro is counterattacked by bullies who discover that Mahiro is a woman. At first, Mahiro is very optimistic, but gradually falls into masochistic pleasure, drowning in lust and being disturbed.