My friend's mother

Hina is her mother who lost her husband two years ago and lives with her son. Due to work, I often moved, so my son couldn't make any friends. One day, my son brought a friend called Yuji home. He is happy that his son has made a friend, but Yuji becomes aroused by Hina's beauty and sexy body, and is raped by her son's unaware... and Yuji becomes radical as Hina does not resist for his son's sake...