Helping sister-in-law Tsubasa Amami get pregnant

I asked my brother-in-law to help me give birth to Tsubasa Amami. A guy has been married for three years but they haven't had their first child yet. He went to many doctors and concluded that his sperm was diluted so it was difficult for Tsubasa's wife to get pregnant. There is another man in the house, his brother-in-law, who is strong and looks like a gangster. Tsubasa and his wife thought of a way to ask for their younger brother's sperm to conceive because they were of the same bloodline. A truly crazy thought but they actually did it. In the movie, the husband silently tolerates his wife and younger brother making love and secretly rejoices.