Marina is glad that her son Kiyoshi is hanging out with friends, namely Yuzuru, a friend of the family.
But be careful what you wish for. Because Yuzuru is finding out about females and he unexpectedly made an awkward move on Marina, who obviously refuses him kindly. But Yuzuru takes it badly and grows an inner grudge.
Yuzuru gathers some friends and bullies Kiyoshi, in order to get to Marina. And it all leads to a savage gangbang fiesta.
Marina, one more time, just amazing.