He appreciates the consideration, he truly does, but leaving that decision up to him is a lot. Shinji doesn't want to make Kai keep secrets, especially not when the truth has a way of making itself known sooner or later in a place like this. He doesn't want to give the go-ahead to something that might damage his relationship either, or just as bad, jeopardize his standing with Kyoko. If Kai tells her this, surely it would leave her under some kind of pressure. Surely she'd feel awkward around Shinji after it.

And that... would be extra bad, especially when they have plans for the immediate future that require them to work together. Shinji is... relatively confident that he can keep this secret under wraps and act normally around her at least as long as those plans require it for, but if Kyoko knew...

"I won't tell you not to," he says carefully, wringing whatever assurance he can from everything Kai has to say. This isn't because of anything Shinji is or isn't doing, this isn't some kind of attempt to put him at arms length. "But... if you do decide to... can it wait? Maybe... a week, at least?"

He needs that much promised to him before he can touch on those other sentiments more meaningfully.