[EXbob]

Originally Posted by Ithekro

Not sure if that stuff exactly, but Tsuruya is more clever than she seems.

Spoiler for Light Novel 7:

She's the SOS-dan's honorary member. She gets along wth Haruhi easily like a friend. They tend to have similar ideals. Tsuruya's family is rich and has lots of land that Haruhi uses from time to time with permission from Tsuruya. Add to this that Tsuruya's family provides funding for Ituski's Orginization, we have someone who probably knows more than what she lets on. She will take in a time traveling Mikuru for a week when there are two around at the same time. She's friendly with all the SOS-dan members. She seems to have decided to observe and not poke into things, as what Haruhi and her group gets into is usually fun in some way.

So, she's just along for the ride and doesn't care what they are?