Cy-Believers Vol 1

Cy-Believers by Shioko Mizuki. A Comedy manga rated Older Teen.

Rui Kobayakawa enrolls at the elite Domus Aurea School to get away from her family, only to discover that her arranged fiance, Natori Nijo, runs the school's oppressive Public Safety Commission. Required to join a club, she falls in with the Believers, a tiny offshoot of the Public Relations Club, and when they're branded worthless, Rui pushes them to strike out on their own as the Cy-Believers. A zany school comedy.