My childhood friend Rio and my respected big brother. Rio, who has returned to her hometown for the first time in a long time, goes to see her unrequited love brother. And she was dressed in metamorphosis underwear by her big brother who had become a chara man different from the old days, and she was copulated in the shade of a tree in the park. There is a relationship that only I do not know between the two people I loved ... I am ...!?