That composer was just horny, come on Pregnant Ai-chan 2.0 in the making!!!

Anyway, not sure why you'd be disappointed in Aqua. He was sure the villain was his biological father. That father is confirmed dead. When he found out, all the tension suddenly fleed him. I understand that. Imagine you've been learning for an important test, only to find out the day before the test that everyone passes automatically due to some new rule. You'd lose all the built-up stress from one to the other moment.

That said, I don't believe it's that simple either. My first thought was that the half-brother himself is the evil guy or at least part of it. First of all, we don't know if he's even telling the truth. Secondly, he said he hated his father. That's a pretty severe thing to say for someone who just slept around with women and wasn't successful at his job. Considering that Himewaka has been portrayed as pretty smart, too, I can see him being the bad guy. Setting up the murder of Ai-chan who, in his eyes, caused his parents' double suicide. Or maybe he caused the double suicide, too, because his parents' relationship was made miserable by the dad's affair with Ai-chan and he did a tabula rasa on all of them.

Fucking hate the new, grey haired girl. Pls don't let her be a reincarnation of Ai-chan, sigh.