Kokoro is a girl that works with her two older sisters at a library with the same name at hers. The problem is that the library is far away from the nearast town so people seldom come to the library. Follow Kokoro and her sisters as they try to uphold the legacy of their father.

It's a lighthearted, slice-of-life manga.

From Viz:
The trouble and fun began when ordinary teenager Tenchi Masaki inadvertently released the legendary demon Ryoko from his grandfather's shrine. Turned out Ryoko was actually a marooned space pirate! Since then, she's become Tenchi's unwanted houseguest, attracting a host of other troublemaking alien women: Ayeka, a haughty alien pricess; Sasami, her mischievous little sister; and Washu, Ryoko's mad-scientist "mother." Add Ryo-oh-Ki, an adorable little carrot-eating spaceship, and you've got one full Shinto shrine!