So there are 3 outcomes after the conversation with Shoichi. The first one is letting it go instead of pushing him about his situation with his mother. This is kind of the middle ground. Not good, but not as bad as it could have been. The worst outcome is when you keep pushing without picking the right choices. And it is heartbreaking. The best one involves you to SPOILERS:
Day 22: Choose "I still mean it." and "Ignore your Father!"
Day 24: Choose"I can't bring myself to stay quiet."
Day 26: Choose "Be firm" and "keep pushing"
This will lead to an emotional reunion with his mom.