Umi never did anything that warrant all the hostility he's receiving from half the readers yet somehow he must be a planning to destroy Kazuya scumbag, just why? I'm 99% certain he's just a normal nice dude who liked Chizuru a bit and is getting over it by now because that's what you normally do, especially when being as socially succesfull, popular and confident as he is you just take the rejection and move on with your life. You're all too afraid of being cucked. The next drama will come from Mami not him.