From Tokyopop:

When mysterious phenomena rock the CLAMP campus, there's only one group to turn to - the Paranormal Investigators, skilled at getting to the bottom of all things otherworldly!

This kooky cast of characters, loosely based on the CLAMP artists themselves, will take you on a wild journey through their own adventures and misadventures. When the three-volume series wraps, you'll be left with a lasting impression of the multitude of mythology haunting both CLAMP School and the Paranormal Investigators.