Miharu Rokujou, an apathetic fourteen-year-old middle school student, is attacked by the ninja village Iga's Grey Wolf organization. They claim he holds Nabari's coveted secret art, the Shinra Banshou, which allows the holder to control creation. As his teacher Tobari Kumohira and classmate Koichi Aizawa, both ninja, protect him from the ninja, Miharu hears the voice of the Shinra Banshou's spirit.
|“||The Secret Art with which it is said one can rule not only the world of shinobi, but the surface world as well. "Shinra Banshou." He who would stand above all things would best desire it.||”|
The story begins with Kouichi being hassled by members of the basketball club for attempting to put up posters for the nindou club. Miharu, noticing Kouichi's futile insistence that his hobby is not out-dated and that ninjas do still exist in the present day, comes to his defence claiming to be a ninja himself, diffusing the situation.
After thanking Miharu for his help, Kouichi tries to recruit Miharu to his club, who hasn't the slightest interest in joining. Miharu mentions that Kumohira-sensei, the club's adviser, had also tried recruiting him to the nindou club, and questions why they would even want to start a nindo club in the first place.
As though summoned by his name, Kumohira appears via a trap door hidden under the stairs, playing his running into Miharu and Kouichi off as a mere coincidence. Kouichi explains that Miharu still has no interest in joining, much to Kumohira's dismay. Not taking no for an answer, the two persist in trying to persuade Miharu to join, and Kumohira ultimately lets slip their real motive: that people are after Miharu, and he needs to learn to protect himself. Despite being vaguely aware of this himself, Miharu still has no intention of joining and manages to slip away with Kouichi. When Miharu and Kouichi split paths on their way home, Kouichi notices that a mysterious power has begun to manifest around Miharu, who remains oblivious of the plants magically growing beneath his feet.
Kumohira, ever insistent, visits Miharu's family's okonomiyaki shop in hopes of continuing their previous conversation which Miharu had cut short. He explains the current nature of the hidden and surface worlds, and that he is also a shinobi. Miharu does not believe his story, and as usual, begins to egg him on which causes Kumohira exclaim that he needs to take him seriously or else he might be killed. Still, Miharu insists that he has absolutely no interest in becoming a ninja.
Further ending the conversation, Miharu volunteers to buy some more katsuobushi for his grandmother and leaves the shop. On his way to the grocers he runs into Kouichi being harassed by a couple of indiscreet ninjas and calls out to him but is himself ambushed by another which had been hidden. Much to the ninja's and Miharu's surprise, Miharu is able to fend off his attacker, buying Kouichi enough time to transport the two just out of harm's way. Recognizing that the ninjas are after him and not Kouichi, Miharu rushes right back to their enemies and tries to diffuse the situation, stating that he has no knowledge of any secret art. The ninjas reveal that the secret art is not something he knows but rather something inside him which their chief desires to reign over the world.
Kouichi again comes to Miharu's aid, however this time, the Shinra Banshou also exposes herself and makes a suggestion to Miharu to end this fight for good: to kill them all.
Thus, the secret art activates.
In fear of the secret art and the forces of nature spewing from its activation, the enemy ninjas attempt to flee. Kouichi, however, stands firm and in a last ditch attempt to stop the art stabs Miharu straight through the chest to seal it just as Kumohira arrives on the scene and Miharu, slumped over and covered in blood, begins to come back to his senses.
- Miharu Rokujou
- Tojuro Hattori (Cameo)
- Raimei Shimizu (Cameo)
- Yoite (Cameo)
- Kouichi Aizawa
- Tobari Durandal Kumohira
- Miharu's Grandmother
- Unnamed Iga ninjas
- Shinra Banshou
- Kouichi is revealed to be in class 2-4.