Originally Posted by
shinta|hikari
We have lots of hints of her manipulation. Even her declaration of her love for Haruki to Touma, the confession right after the live, her apology to Touma (making Touma pull back and give up), calling Touma her best friend (this was really unnatural. Touma does not treat anyone well enough to make them think they are best friends), meeting Haruki behind Touma's back, the hot spring trip that was designed to keep the 3 of them together, and now this birthday plan all point towards that.
She isn't a criminal mastermind or anything. It's just that compared to the other two, her plans and actions have influenced the situation (and the others' behavior) far more than the others.