I never understand what is Tsukihi's stereotype.
Karen and Mairu is obviously one dimensional genki girl.
Kururi is oppai megane+kuudere
Tsukihi isn't tsundere enough, isn't a yandere and obviously isn't a kuudere, then what is she?
Tsukihi is irrelevantdere. She has literally no screen time. Her bathing scene with Araragi in Tsukimonogatari was longer than all the other scenes she was in up until that point combined.
But if Araragi and Karen previous scenes are anything to go by, yandere describes her the best.