The Seven Deadly Sins, along with Elizabeth Liones and Hawk, have won the Kingdom of Leones back from the Holy Knights. At long last, it's their time to indulge in the peaceful lives they fought for. From inedible meat pies, overdue battles, unexpected stalkers, and the butterflies of first love, the Sins are accompanied by their friends in their carefree, fun-filled time together. However, the calm is broken with the premonition of a new threat, bringing upon the signs of Holy War and threatening to shatter the peace of the Sins' easygoing days.

Blessed with eyes that are able to perceive the otherwise invisible youkai, Takashi Natsume hides his ability from his newfound family and friends to protect everyone's peaceful daily life. Nonetheless, Natsume never fails to show the same kindness to the benevolent youkai and happily returns their names by using the infamous Book of Friends he inherited from his late grandmother, Reiko. Meanwhile, the exorcist clan Matoba still wishes for Natsume to join their ranks due to his overwhelming gift. However, Natsume firmly rejects the clan's invitation since not all exorcists are as reasonable as his friend Shuuichi Natori, and many improperly and indiscriminately seal away every youkai in their way. Unsatisfied with Natsume's answer, Seiji Matoba blackmails Natsume into attending a grand gathering of powerful exorcist families. Natsume soon finds himself in the company of dangerous people and youkai alike. But even then, he continues to defy the exorcists' hard-handed methods and believes that peace between both worlds is possible.

Takashi Natsume and his spirit companion Madara, nicknamed Nyanko, continue returning the names of spirits from the Book of Friends given by his late grandmother Reiko Natsume. On his way back from school one day, Takashi encounters a lurking spirit named Monmonbou, who recalls memories of Takashi's grandmother after hearing his name. Takashi's natural curiosity leads him to explore a mysterious town where his grandmother used to live. Befriending her old acquaintance Yorie Tsumura and Yorie's son Mukuo, Takashi unveils more of his grandmother's past. In the meantime, Nyanko detours for food and stumbles upon a suspicious Spirit Seed, which miraculously sprouts into a fruit tree overnight. Giving in to temptation, Nyanko consumes the fruit, splitting him into three. Seeking a solution to Nyanko's predicament, Takashi and his friends lend a hand, unexpectedly uncovering more secrets the town holds in the process.

Ishi Okoshi While searching for Nyanko-sensei, Takashi Natsume encounters meek and small-looking youkai Mitsumi. Mitsumi was entrusted by his leader Gantetsu, a powerful and strong ayakashi, to be the year's Ishi Okoshi, whose role consists of waking him from his deep slumber. Seeing how much Mitsumi wants to prove himself as Gantetsu's worthy servant, Natsume decides to help him fulfill his task. However, time is running out—for they are not the only ones who want to awaken the divine being. Ayashiki Raihousha One day, Natsume's friend Kaname Tanuma is visited by a strange man. In the subsequent days, the visitor briefly talks with Tanuma and leaves. Natsume soon discovers that the outsider is a youkai disguised as a human, who claims to bear no danger. Despite trusting the youkai, Tanuma's health slowly begins to deteriorate, causing Natsume to become more suspicious of the interloper. What is the truth of his sudden appearance and his connection with Tanuma?