The story centers on a teenage orphan named Takashi Natsume. Natsume apparently just a normal guy, but has the ability to see spirits, a power inherited from his grandmother, Reiko. After his death, Reiko bequeaths to his grandson only membership - the Book of Friends, a book containing the names of the spirits that Reiko had bullied into signing a contract and become his follower.
For the first season, the opening theme was "Issei no Sei" (Simultaneous Voice) by Shuhei Kita, and the ending theme was "Natsu Yuuzora" (Summer Evening Sky) by Kousuke Atari. The Book of Friends is a very appreciated in the spirit world, and therefore these constantly harass Natsume.