isn't really suspicious in the evil sense (if that's what you meant by "sus"). While she does talk/act like a goody-two-shoes in front of Tenjouin, she is actually like a love-predator type of person, who would do anything to get the person she likes (though she isn't on a Yandere level, and actually sees Miki as a Love Rival and even is accepting if Tenjouin goes the harem route, though Miki wants monogamy route only and doesn't want anyone else to go after Tenjouin).