The older sister is responsible.
The younger brother is extremely lucky to have a sister who loves him wholeheartedly. Besides being good at cooking, the girl always takes a short time to care for her naughty younger brother (actually, the name of the male actor is very old now).
In addition to being responsible for household chores, the sister is also very lustful, incest with her younger brother seems to have become a habit, like her daily job...
