Sagami decided to harass Yuudai saying he would leave Futaba alone, if he didn't interfere wit him getting involved with Ichiyo, Yuudai didn't agree to that trap, it would only hurt Ichiyo if he did, and he wasn't going to allow her to be hurt if he could stop it. Sagami thinks if he acts as he wants he can get his way, he doesn't understand when people don't cooperate with him, he's used to having the power of his father behind him, his father and him don't comprehend people that are in a weaker position and don't back down, and also they don't realise how much there influence and power has waned, they believe their troubles are unknown.