My theory is that if Kirari gamble against her other half (Ririka), no matter if she win or lose, she won't be the Kirari that Yumeko wants to play with. Maybe for Yumeko, Kirari will inevitably change if she deviate from her twin, so she will never be against the president because the president she want to fight won't exist anymore.
I hope it's understandable, english is not my first langage
So suji arrived just before the 13th game and the 16th game is when the whole thing went down. That mean that she destroyed the game in 3 months. She doesn't do things in moderation.
IKR she's the moment!!!