Violent father Moo-jin, whose family is everything. Mother So-yeon left because she couldn't stand the violence. Hoon, who loves both his father and mother, is forced to make a choice and leaves, but eventually remains alone and enters his world.

The 'boy' fights with his mother from morning and leaves home. On the bus to the mountain, he meets 'younger sister' and her 'older sister', who go hiking after a long time. However, the 'boy' was kicked out of the bus after being found to have paid less bus fare.