Lustful sister-in-law solicits sex from her lustful younger brother

My sister-in-law seduced me when I returned to Riho Fujimori's house. A guy went to work far away and after a while returned to his hometown to live with his family. Here there is a brother and sister-in-law along with an old mother. Even though he's almost thirty, he's still single and funny and handsome, so even though he's his sister-in-law, Riho still likes him very much. And then one time he saw his sister-in-law and brother having sex in the room. Riho knew that and took actions to provoke this young man. And then whatever will come will come, he cannot escape the love net that Riho has set.