Yuya buried his head in his futon miserably...
In the next room he could hear his mother and stepfather making love....

It used to just be him and his mom. That life was fine. Suddenly now he had a dad?
Some stranger worthy of sharing the same life, the same woman. Having sex with her.
Yuya's fury could scarcely be contained. His anguish carried through the night.

The next day his stepfather went out, and Yuya and his mom were alone.
Miki didn't like that her son and her husband weren't getting along, and she wanted to
see them become better friends, she told Yuya. It was like throwing oil on fire.

Yuya suddenly snapped and lunged at her. "How can you be turned on by him!
I can't stand it any more. If you need to be satisfied I can do it!" he yelled.

Miki tried to resist him and calm him down, but it was no use.
"My own son is inside me..." was all she could think
as her soul shriveled and fell endlessly to the bottom of shame.

[From DLsite - ENG]