Asumu Adachi and his mother went to Yaku Island for a family reunion. During the boat ride to the island, Asumu meets a man named Hibiki, who has just saved a child from going overboard. On Yaku Island, people are disappearing in the forests and Hibiki goes in to investigate. In the forest, Asumu and his cousin meet Hibiki and also run into a pair of demons known as Douji and Hime of the Makamou. Hibiki goes to fight the Makamou and transforms into an armored figure called an Oni. When cornering one of the Makamou, Hibiki is seen by Asumu.

Hibiki spends the night at the memorial where Asumu is staying. The next day Asumu meets Hibiki out by the beach and they both talk about what Hibiki does for a living. Asumu witnesses Hibiki transform into the Oni to fight the Hime and her child, a demon-spider called Tsuchigumo. After the fight, Asumu begins to take a liking to Hibiki.

Both Asumu and Hibiki return to Tokyo where Hibiki is sent off to defeat a Yamabiko sighted at Okutama. Later on, Hibiki meets Asumu's mother, who is ecstatic to see him. The strain of studying for entrance exams begins to trouble Asumu as he worries about Hibiki and how safe he is with the type of job he has.

Asumu trails an old man whom he believes has connections to Hibiki after he sees him save a young girl. Elsewhere, Hibiki continues his battle with the Makamou who had been killing people in the forest. After the battle, Hibiki and Kasumi return to Tachibana's sweet shop, where Asumu and the old man are.

Hibiki and Asumu have a talk about the school that Asumu wants to go to. At school, Asumu is told by a teacher that if he fails his entrance test to Johnan, he will have no second chance so he must not fail. Hibiki is then told of a Makamou, called Bakegani, that has been attacking ships and defeated a fellow Oni, Zanki. He goes to fight the Hime, but was overcome by the Bakegani and is forced into the sea.

Ibuki, thinking Asumu is Hibiki's student, takes Asumu to where Hibiki and Kasumi are located. Hibiki and Asumu have a discussion about life and the challenges that everyone faces, leaving Asumu with a renewed passion to do well on his entrance exams. Hibiki then returns to battle the Bakegani that defeated him previously.

Ibuki appears and mistakes Asumu for Hibiki's student, taking him to the sight of a battle. Asumu then joins Hibiki and Ibuki on a trip to defeat an Ittanmomen at Okukuji, where Asumu meets Ibuki's student: Akira Amami.

An irritated Akira tells Asumu that he will only hinder Hibiki if he continues following him around and that it would be best for him to leave. Asumu wonders just how true her words are and asks Hibiki himself how he feels about it. Ibuki then defeats the Ittanmomen and Akira and Asumu make amends with each other.

Spring break has started and Asumu has already gotten off on the wrong foot, having missed going to the movies with his friend. He spends the rest of the day wandering around town and eventually encountering shoplifters.

Asumu continues to wander through town after being a witness to the shoplifting, not really sure of himself and what to do next. Hibiki and Ibuki team up to take down a very rare Makamou, Otoroshi.

A new school year has started and Asumu enters high school but still has mixed feelings on the path of life he has taken. Through all the aimless wandering he finds himself back at Tachibana's Sweet Shop.

After going through a false wall in Tachibana's Sweet Shop Asumu stumbles upon the Oni R&D room where Midori shines some light on Hibiki's past.

Hibiki goes to Asumu to ask him for a favor but Asumu doesn't seem to be feeling well.

Asumu is hospitalized and undergoes emergency surgery after collapsing in class, his high school life comes to a halt until he heals.

Asumu returns home after spending a week hospitalized and begins his recuperation. Elsewhere, Zanki reveals that he will soon be retiring and expects his apprentice Todoyama to take his place, a revelation that Todoyama is less than pleased with. Even more, they are called to aid Sabaki at Tsukama Village, where a Yamaarashi is running rampant.

Zanki and Todoyama come to Sabaki's rescue after being captured by the Yamaarashi. Zanki begins to weaken and proves unable to defeat the Yamaarashi. Todoyama takes Zanki's place and destroys his first giant type Makamou. As Zanki retires, Todoyama refuses to take his name, instead wanting to make a name for himself, Zanki dubs him Todoroki, the roaring Oni.

Kasumi and Ibuki go clothes-shopping on their day-off. After shopping and during their meal, Ibuki sees a Douji and Hime pair in the city and begins his pursuit. Elsewhere, Hitomi is having mixed feelings about Asumu and Akira spending so much time together. After defeating the Douji-Hime pair, Ibuki is attacked by an Oonamazu stomach. After its retreat, Ibuki calls Akira and asks her to bring his Reppu.

Akira makes her way towards the ever-changing location of the Oonamazu. Asumu then heads to Tachibana's and ends up helping Hinaka deal with the influx of customers. Later, Ibuki once again takes on the Oonamazu stomach, only to be severely burned by its stomach acids. As she heads towards the battle, a puppet-type Makamou causes Akira to collapse under a bridge. Ibuki then proceeds to fight the Oonamazu for the final time.

Asumu begins his first day at Tachibana's Sweets Shop and discovers that Todoroki and Hitomi are related. Todoroki continues to fight the Bakegani as Kasumi notices something is wrong with him. Zanki later arrives after he is called by Ichiro to examine a recording of Todoroki's peculiar fighting style.

Zanki visits Todoroki on the battlefield to question about his style of fighting. Asumu begins to have troubles at Tachibana's and is then pulled into a conversation with Ichiro about the Oni. Hibiki later joins Todoroki in a fight against an Amikiri. Zanki later makes a decision about his and Todoroki's future.

Ibuki and Todoroki, separately, are following two groups of Makamou that are heading towards Mount. Asama. The oni find it strange that the Makamou don't want to fight nor do they attack humans; what is at the top of the mountain that draws them?

Ibuki and Todoroki combined their strengths to defeat the pair of Douji and Hime, but the Ubume and Yamaarashi are nowhere to be found. What they do find is something like the two Makamou but cannot be defeated by their string and wind Ongekis.

Hibiki takes Todoroki to his mountain top training temple to teach him how to play the taiko. Unfortunately, the training seems to be too intense for him.

Hibiki and Todoroki's training is stopped midway because they get a call that a villiage nearby has been attacked. They arrive to the seen and realize that the Makamou is a self multiplying Dorotabou, which can only be defeated with the taiko based Ongeki.

After Sabaki is defeated by a Kappa, Hibiki is sent out to finish the the job. Asumu, Hitomi, Hinaka, and Todoroki enjoy the day off by going to a water park. At the park they run into Tsutomu Tsumura, who works at the park but has ties to the Oni world.

Everybody is out, either enjoying their day off or hunting down Makamou, leaving Asumu and Akira to tend to the sweet shop.

Hibiki, Todoroki, and Zanki track down the group of Bakeneko hiding in the forest shrine.

After being beaten up by the shoplifter (first seen in A Squirming Evil Heart) Asumu loses his normal cheerfulness. Hibiki sees this and decides to take Asumu for a forest hike.

Asumu slips and falls while descending a hill causing him to loose his cellphone and Hibiki to loose his cowboy hat. Asumu blames himself and Hibiki confronts the boy about being too negative and self-consciousness.

A new boy has transferred to Asumu and Hitomi's school, Kyosuke Kiriya. Kyosuke is good at everything from language to sports and makes Asumu feel boring.