I wanted to give this game a chance, but..
The reason the mother drugged MC was to make her daughter happy (mc sister)
It's as if she didn't care for her son at all and her daughter was more important to her..
Who normal drugged his own child?.. It's too much for me. The explanations are not logical to me.
Even though the MC is angry with them, he forgives them too easily.
I give up playing this game. This is not for me, I hate drugs.
Additionally, I often cannot understand the sentence well. I often finds mistakes in words and sentences. Although I am not good at English myself, because it is not my native language.
Anyway.. good luck!
Unfortunately, I give up.