I didn't really think Yako would be stopped by something like "Senpai already has someone he likes."
If she's a character deliberately being introduced to mess things up in a story like this, you can bet she WILL mess things up and not immediately give up in like the second chapter she appears in. I can respect Yako's chaotic hustle. Umimi be like: "You're going after him even after he already likes someone else? Wait, that's against the rules!"
Before Yako came along Umimi was the closest thing to a character I could like in this manga, but her schtick of always lying to herself really grew thin with me. I don't even believe Umimi going on the attack coming after Riku in the boys' toilet will lead to
something.
Something happening in
this manga? No way.
I'll say it again, Yako is Riku's ticket to exiting this quagmire his friends made for him. If only he himself wasn't
super crazy over maintaining his childhood status quo with Shizuku and Takt. She may be rehashing Umimi's initial role of throwing a wrench into the equation, but boy if she isn't a breath of fresh air into this series. I'm not even mad this is technically a regular harem now with 3 girls chasing after Riku.