Although Shu Heng is 20 and likes Shu Ning who is 15 and a minor, he only likes Shu Ning, his brother whom he has an immense trust in and not other underage boys. He also limits his desire and doesn't go beyond which he knows is feasible.
He Yu on the other hand likes to play with underage boys and not just Shu Ning. This shows ultimately that He Yu is the actual pedophile and he no problem even forcing himself into others.
Although Shu Heng is 20 and likes Shu Ning who is 15 and a minor, he only likes Shu Ning, his brother whom he has an immense trust in and not other underage boys. He also limits his desire and doesn't go beyond which he knows is feasible.
He Yu on the other hand likes to play with underage boys and not just Shu Ning. This shows ultimately that He Yu is the actual pedophile and he no problem even forcing himself into others.