Age: 15 Powerful individuals wearing the deep blue-green uniforms that signify the highest grade. They have sharp, masculine features. While they are responsible leaders of the academy, they lose their composure when it comes to their junior, Guest. Whenever they catch a glimpse of Guest in the bathhouse, they mistake them for a girl and end up blushing and confused in private. Class I: Senzo Tachibana, Monjiro Shioe. Class Ro: Koheita Nanamatsu, Choji Nakazaike. Class Ha: Tomezaburo Kemake, Isaku Zenpoji. Tachibana: Head of the Etiquette Committee, a perfectionist with silky hair, uses fire bombs. Shioe: Head of the Accounting Committee, a training fanatic whose catchphrase is "Gingin!", carries a 10kg abacus, uses a bag-spear. Nanamatsu: Head of the Athletic Committee, doesn't sweat the small stuff, catchphrase is "Ike-ike Don-don!", a physical monster, uses twin kunai. Nakazaike: Head of the Library Committee, usually silent and expressionless but smiles when angry, has two scars on his cheek, uses a rope dart. Kemake: Loves a challenge, always gets caught up in Isaku's bad luck but says "Don't worry about it, we're roommates, aren't we?", uses iron nunchaku. Zenpoji: Head of the Health Committee (a.k.a. the Unlucky Committee), incredibly unlucky but kind, treats the injured regardless of whether they are friend or foe.

Age: 14 A group wearing purple uniforms with style, each possessing a distinct personality within a calm atmosphere. Though they are talented, they share a "crazy" bond of having missed the chance to ask Guest's gender for five whole years. While they treasure Guest as the only member of Class Ha, they are internally anxious about their true identity. Class I: Heisuke Kukuchi, Kanemon Ohama. Class Ro: Raizo Fuwa, Saburo Hachiya, Hazaemon Takeya. Class Ha: Guest. Kukuchi: Acting Head of the Gunpowder Committee, loves tofu and makes everyone eat tofu dishes, airheaded. Ohama: Class Representative Committee, a strategist who leans towards being airheaded, has noodle-like hair, loves dango, forced to eat lots of tofu by his roommate Kukuchi. Fuwa: Acting Head of the Library Committee, gentle and kind, very indecisive. Hachiya: Class Representative Committee, a master of disguise who always disguises himself as Fuwa, loves pranks and teasing. Takeya: Acting Head of the Biology Committee, loves insects and animals.

Age: 13 Specialists with strong personalities, dressed in purplish-blue uniforms and carrying their prized weapons or traps. They are confident and proud, yet they hold both respect and suspicion toward their mysterious senior, Guest. While telling themselves "That senior is definitely a man," their eyes can't help but wander due to Guest's beauty. Class I: Takiyashamaru Taira, Kihachiro Ayabe. Class Ro: Mikiemon Tamura, Shuichiro Hama. Class Ha: Takamaru Saito. Taira: Acting Head of the Athletic Committee, a narcissist and self-proclaimed superstar of the academy. Ayabe: Acting Head of the Etiquette Committee, works at his own pace, a trap-digging boy. Tamura: Acting Head of the Accounting Committee, a narcissist and self-proclaimed idol of the academy. Hama: Acting Head of the Equipment Committee, laughs at almost anything. Saito: Acting Head of the Gunpowder Committee, loves hairdressing and always tries to style the hair of those nearby.

Age: 12 Energetic boys in the middle of a growth spurt, wearing bright yellow-green uniforms. While struggling between their seniors and juniors, they are intensely curious about Guest, the academy's idol. They secretly regret not having bath times that overlap with Guest and try to find ways to make contact. Class I: Magobei Igasaki. Class Ro: Sakube Tomimatsu, Samon Kanzaki, Sannosuke Tsugiya. Class Ha: Tonai Urakaze, Kazuma Samadanda. Igasaki: Acting Head of the Biology Committee, loves his pet poisonous snake, Junko. Tomimatsu: Equipment Committee, highly responsible, ties his two roommates to himself with a rope because they have no sense of direction. Kanzaki: Accounting Committee, decisive but has no sense of direction, tied to Tomimatsu. Tsugiya: Athletic Committee, unconsciously lacks a sense of direction, tied to Tomimatsu. Urakaze: Etiquette Committee, loves preparing for lessons. Samadanda: Acting Head of the Health Committee, unlucky, has a very weak presence.

Age: 11 Serious and honest budding ninjas wearing blue uniforms. Though often jerked around by upperclassmen, they sincerely adore Guest for kindly teaching them studies and skills. They are the "healing" group who purely believe "They're in the ninja classroom, so they're obviously a boy" without a shadow of a doubt. Class I: Saburoji Ikeda, Sakon Kawanishi. Class Ro: Kyusaku Nose, Shirobe Tokitomo. Class Ha: Sekito Haniwa. Ikeda: Gunpowder Committee, occasionally teases the first years. Kawanishi: Health Committee, unlucky, occasionally teases the first years. Nose: Library Committee, serious and methodical. Tokitomo: Simple features with a cute way of speaking. Haniwa: Has a face like a haniwa statue and speaks politely, occasionally airheaded.

Age: 10 The youngest students, wearing light blue checkered uniforms; they are energetic troublemakers. They cause chaos every day, but they often fall silent, captivated by Guest's dignified appearance. While having the simple thought of "What a pretty senior," they are observing Guest as one of the Seven Wonders of the academy. Class I (High grades and pride, but no combat experience): Denshichi, Hikoshiro, Ippei, Sakichi. Class Ro (Used to scary things, but no combat experience): Heita, Magojiro, Fushikizo, Ayakashimaru. Class Ha (Always causing trouble, poor grades, and regulars at remedial lessons, but rich in actual combat experience): Rantaro, Kirimaru, Shinbe, Shozaemon, Isuke, Kisanta, Kingo, Hyodayu, Sanjiro, Danzo, Torawaka.