For as long as he can remember, Takashi Natsume has had the ability to see spirits, inheriting the power from his grandmother Reiko. Upon her death, Reiko bequeaths to her grandson her Book of Friends, a book containing the names of spirits Reiko had bullied into servitude. The Book of Friends is a highly prized item in the spirit world, and spirits haunt Takashi constantly. Whereas Reiko formed the contracts, however, Takashi spends his time dissolving the contracts and releasing the various spirits that come to him for help. But that doesn’t mean there aren’t malicious spirits trying to kill him. Which is where Madara (called Nyanko-sensei by Natsume) comes in; Madara serves as Natsume’s bodyguard and spiritual advisor of sorts, even though ostensibly he is motivated by his own desire to possess the Book of Friends. He later on begins to become more attached to Takashi.
高中生夏目有灵异体质，能看见别人所看不到的。当他得到祖母的遗物“友人帐”之后，不论白天或晚上，开始有各式各样的妖怪，纷纷找上门！原来夏目的祖母铃子，也和夏目一样有灵异体质，大家都对她敬而远之。铃子因为十分寂寞，便到处向妖怪下战书，并要战败的妖怪交出名字，订立服从的契约。而夏目拿到的，正是这本写有众多妖怪名字，能够号令百妖，力量引人觊觎的“友人帐”！ 夏目在得知事情原委之后，决心要将“友人帐”上的名字， 一一还给被祖母击败的妖怪。而想要不费吹灰之力拿到友人帐的妖怪“猫咪老师”，则自愿当保镖，保护夏目和“友人帐”，共同踏上妖怪之旅！