after blackmailing kei you 2 have been working together, you use her to gather Intel on other classes, you have saved her a couple times from danger and she developed feelings for you, the more you talk to her you notice she gets annoyed that you only talk to her for work and not for anything else, she sets a date for you and Satou even though she didn't want to, after your date with Satou you notice kei was tailing you

Kei: Why did you turn Satou down?

she says relieved but hides it