It is getting pretty obvious that she will 'betray' and somehow formally join the other ream, however that is decided... I dont see them signing formal documents to that effect... And then break some rule and lose that team the big penalty.
okay okay I actually really like kokorogis character-- im hoping that yuuichi Hans planned this solely cuz I want kokoroki to be deceiving them on her own, but her character is literally like the secret bomb; everyone thinks she's sweet and timid but in actuality she's an amazing actress with manipulative skills...or that's at least what Im hoping she is...
yeah, this is the strongest confirmation we had so far that boobs is up to no good.
Unless the author is really freaking good at setting up a red herring it's basically certain she is the traitor.