Nope. yagami was the princess that daikoku fell in love before. The mc uke is said to be her reincarnation, daikoku thinks that his brother is after the uke becuse of this.
Maybe you mean yasogami? Daikoku's brother? If yes, he was the fiance of Yagami, the princess but she chose Daikoku instead of Yasogami. They didn't mention why but Daikoku hates him. Maybe he was the caused of the princess death?
Well, i think watanabe should be punished a lil bit more before they are finally together. Because hazuki is really kind and sweet, he deserve so much better
The girls are not innocent. They know everything lol