The apathetic 14-year old protagonist of the series. Although Nabari's most powerful secret art, the Shinrabanshou (lit. All Things in Nature), is literally written into his body and he is venerated by all of Nabari's ninja as king, Miharu cares little about his gift's profound merits. His only goal is to inherit the family's okonomiyaki store.
Birds of a Feather: Seemingly the basis of his friendship with Yoite; both are jaded, withdrawn stoics (at first) fighting a war with little personal meaning to them. Miharu even calls Yoite "another me."
Say My Name: Says Yoite's name a lot, though given his subdued nature it's less loud than the the typical example. Becomes a Crowning Moment of Heartwarming in the manga's last chapter when he calls Yoite's name as they reunite, and repeats it while gazing at the scar on his hand after they separate.
Scars Are Forever: The scar Miharu gets on his hand from stopping Yoite from killing Yae Oda is brought up again at the very end of the manga.
One of Miharu's classmates, Aizawa is the leader of the school's Nindou club. He's actually an owl with a human heart who was made immortal by a previous hijutsu user. He and Shijima both want Miharu to free them from the "curse" of immortality.
Badass Bookworm: Aizawa Kouichi seems like a mild-mannered and well-spoken young man often taken aback by his friends' quirks and isn't the best at ninja techniques...except when push comes to shove, he becomes a cool, level-headed, and actually professional ninja who doesn't hesitate to kill, brainwash, and do whatever it takes to free himself from the curse of immortality, even if it means siding with the enemy village.
Red Eyes, Take Warning: While he apparently isn't evil, he's certainly more ruthless than he first appears, and he's definitely planning something behind his team's back. Plus, he's immortal, and not exactly human.
Miharu and Kouichi's 25-year-old teacher in the front world. Born in Ireland, he was forced by his grandfather to go to Japan and learn to become a ninja. Among the Banten ninja, Thobari is the most vehement dissident against Miharu using the Shinrabanshou, instead advocating its permanent seal.
Afraid of Needles: Thobari's irrational fear of vehicles of all sorts. Apparently he used to be an award-winning choirboy in Ireland, but being forcibly brought over to Japan in an airplane traumatized him so much he became tone deaf.
Fatal Flaw: He's morally unable to take a life, which makes it hard for him to protect Miharu. Multiple characters call him out on this. He finally gets over it by killing Hattori in the anime and Fuuma in the manga.
My Greatest Failure: Not protecting Akatsuki, Asahi, and his grandfather and failing to seal the Shinrabanshou. The guilt from this incident weighs pretty heavily on him, compounded by the fact that he's the only person who remembers what happened.
The leader of Fuuma Village. He loves women as he claims that if he had the power of the Shinrabanshou, he would turn the Fuuma Village into a paradise where all the world's women are in love with him.
Camp Straight: Wears a big white bow in his hair, teases male characters and invades their personal space, and talks in an exaggerated, flowery manner...but he also wants to turn Fuuma village/possibly the entire ninja world into his harem.
The leader of the Iga clan and the Kairoushuu. His ideal is to change history and achieve equality among humans with the Shinrabanshou. Hattori takes in many outcasts, offering them a place in the Kairoushuu. Despite this kindness, though, Hattori has little qualms about eliminating those who oppose him.
Big Bad: Seemed to be anyway. In the anime he is one; in the manga...
A 16-year-old ninja who uses the Iga's kinjutsushō "Kira", a technique that shoots the user's ki into the target's body and controls it from the inside out, causing the target's bones to break or their body to completely explode. The cost of using this technique is the loss of the user's life force. When Yoite is introduced, he has only a few more months to live.According to Word of God, Yoite and Miharu are the series' two protagonists despite Yoite's absence after his death.
Ambiguous Gender: Subverted. the reader (and even most characters, apparently) start out believing that Yoite is a boy. Later it turns out that he's actually... intersexual. It doesn't really matter in the long run, though, and isn't gone into in much detail, only the readers now know another reason for his angst and identity issues.
Badass Longcoat: Yoite is almost never seen without some sort of thick, black coat. He won't take it off, even if it's the middle of summer or if he's soaking wet.
Big Eater: Yoite can be seen eating huge amounts of food in the background of various scenes. He'll eat just about anything since his Kira skill is robbing him of all his senses, and has already taken his sense of taste.
Enigmatic Minion: Works a lot on his own, including his request to Miharu. Unlike some of his teammates, he doesn't care about Kairoushuu's mission at all; rather, his greatest desire is for his wish to be granted.
Shinigami: Called one by multiple characters. Flashbacks reveal that he was called this even before he obtained Kira; family members (possibly his parents) claimed he was a shinigami who had killed his mother.
Papa Wolf: Yukimi betrays Kairoushuu, his home and family since he was a teenager, and loses an arm in order to protect Yoite. He also becomes surprisingly protective of Miharu, even before promising Yoite to watch out for him.
A 20-year-old samurai of the Shimizu clan. When he was fifteen, he single-handedly massacred his entire clan, with the exception of his sister Raimei. This action was actually vengeance against his uncle and his gang, who murdered his parents in a coup d'Útat to take over the clan.
Failure Knight: His decision to save Gau despite his being from the surface world stems from the regret he felt from not saving his best friend five years ago.
Heroic Self-Deprecation: Raikou is convinced that Gau won't wake up from his coma because he doesn't want to see his face. Which might be justified if it was anyone else, but it's Gau we're talking about here...
Must Make Amends: After accidentally causing Gau to fall into a coma, Raikou does everything in his power to find a way to save him, including reading tons of medical books and going to Alya Academy in hopes of using Daya on Gau.
Pay Evil unto Evil: Murders people on a regular basis for misusing ninjutsu for crimes like stealing.
Hypercompetent Sidekick: To Raikou. Despite being a very talented swordsman, Raikou isn't very competent in the more real-world life skills, particularly admin work, which is where Gau dutifully and diligently picks up the slack.
Tender Tears: Cries when he meets Raikou for the first time, when Raikou tells him about his past, when he gets slashed by Raikou, when he intervenes in Raikou and Yukimi's fight, when he calls Yukimi on the cellphone, when Raikou gets stabbed, etc, etc...
Undying Loyalty: Completely devoted to Raikou. He only disobeys him once, and was willing to die as punishment for that.
Wide-Eyed Idealist: The most idealistic member of Kairoushuu. He believes they're changing the world for the better and can do so even more using the Shinrabanshou.
Yes-Man: Gau is described as being "Raikou's little yes-man". So much so, that Kazuho and Yukimi are both taken-aback when Gau absentmindedly expresses doubt in front of Raikou on his course of action.
A mysterious member of the Alya Academy Student Council who seems to know more than she lets on. She's actually a cat with a human heart who was made immortal by a previous hijutsu user. She and Kouichi both want Miharu to free them from the "curse" of immortality.
Yamato Nadeshiko: By virtue of being Team Mom and probably the nicest character in the series. The "core of steel" part shows through when she thinks Yukimi might take her hostage; she offhandedly comments that it probably wouldn't work on Tobari.
Action Girl: She appears to be rather skilled in hand-to-hand combat.
A boy Yukimi meets while saving a cat. He's actually Yoite's younger brother, from back when Yoite was named "Sora Koudou."
Abusive Parents: They treated him better than Sora, but still threatened to "make it like you never existed" if he was kind to Sora and tried to make him attack his brother. He tells Yukimi he's estranged from them and is living on his own.