Responses
There's a sequel or extra that kind of explain it. The little brother visited the other brother as an adult. He saw that the older brother was rich but he gave up everything to live a poor life.
The older brother was pretty pitiful. So pitiful that the younger bro gave up on revenge because the older brother seemed to suffer enough.
why does kazoumi love him even thought he pushed him he should hate him..ah i forgot it yaoi and usually logic is out of the window now they open the roof....hahhaha