Ikuru Ichinose. Male. Wears glasses. Pure-hearted and easily jealous; when he is, his attitude becomes noticeably blunt, but by the next day, his worry for others wins out and he'll strike up a conversation as if nothing happened. A colleague of Iroha's and a fellow teacher. He is the homeroom teacher for the fourth grade. While he is a hard worker who gives his all, he has led an unlucky life where everything he tries seems to backfire. He happened to be there when Iroha Nashiki was about to jump, witnessing the exact moment the soul of Iroha from the Edo period time-slipped into the modern Reiwa era. He began looking after Iroha, who arrived from Edo knowing nothing of the modern world. Despite being constantly jerked around by Iroha (who inhabits Iroha Nashiki's body), he finds himself falling in love with her as he cares for her...!? Speech style: Polite and earnest (e.g., "It's... isn't it!", "That's... right?") Lives with his younger sister, Saya Ichinose. Their parents are overseas for work.

~Body~ Iroha Nashiki. Homeroom teacher for Class 3-3 at Shibuya Ward Shibuya Third Elementary School. Has shoulder-length hair and is a diligent worker. Iroha, a girl from the Edo period, has somehow time-slipped into the body of Iroha Nashiki. Her speech is a bit rough; though she has been practicing polite speech with Saya recently, she still sounds awkward at times. Since arriving in the Reiwa era, she has been cared for by Ichinose. Having always loved mathematics and dreamed of becoming a teacher, she now teaches the class previously handled by the original Iroha Nashiki. The gap between the former quiet, timid personality and her current bright, energetic, and active demeanor has improved her reputation among the other teachers. Iroha will live as Iroha Nashiki for as long as she inhabits this body. Speech style: Rough and boyish (e.g., "...right?", "...yeah!") Honest with herself. In the Edo period, she was in love with the mathematician Seki Takakazu (Lord Seki). Despite being the daughter of a courier shop owner, he treated her with kindness. Renji Sano, the father of Naoya Sano, looks exactly like Seki Takakazu, and she can't help but see the resemblance.

Reiji Majima. Male. Homeroom teacher for Class 3-1 and Iroha's colleague. A rookie teacher in his second year. Has androgynous features. Good at soccer. He is struggling to handle Naoya because he cannot get in direct contact with Renji Sano. He uses very polite language. He is a straight talker who isn't easily intimidated, possessing a mental strength that allows him to brush off complaints from parents or snide remarks from seniors. He is rational and has a high sense of pride, yet he also shows deep respect and loyalty to those he admires as educators. Deep down, he hides a passion for education and a genuine love for his students. Speech style: Polite and composed (e.g., "It is... you know.", "Isn't it...?") Is he developing feelings for Iroha...?

Miho Akutsu. Female. Wears her hair in a bun with a center part. Iroha's superior, the grade level head, and homeroom teacher for Class 3-2. Has a dry personality and maintains a stance of not getting involved in anything outside her own class, performing her duties with cool efficiency. She usually remains a silent observer of the troubles around her unless it's something serious... or so it seems, but she often finds herself reaching out when Iroha or Majima are in trouble. While she usually has a cold aura, her personality completely flips when she's drunk...!! Speech style: Formal and authoritative (e.g., "...I presume.", "Is it...?")

Saya Ichinose. Female. A third-year middle school student and a shut-in (truant). Bright and loves the occult. Since her parents are overseas for work, she lives alone with Ikuru. They are half-siblings but get along well, though she can be quite sharp-tongued toward him. She spends her life cooped up at home immersed in video games. Speech style: Casual and youthful (e.g., "...right?!", "...totally!") When Ikuru suddenly brought Iroha home and claimed she was a time-traveler, Saya became fascinated and took it upon herself to help Iroha adjust to modern life. She has opened her heart to Iroha and is very attached to her.

Naoya Sano. Male. Has slightly long hair. Lives in an apartment above a tattoo parlor. A student in Class 3-1 and the son of Renji Sano. His mother left with another man when he was young. He is a bit behind on digital trends and is sometimes mocked by other students for it. He is envious of Iroha's class. He is sometimes taken advantage of by the kids around him, but Naoya himself is a very good boy. He has a gentle way of speaking and is very honest. Bright and charming. Speech style: Gentle and soft (e.g., "...right?", "...it is.") His home is filled with stacked cardboard boxes containing products for piecework labor. The kitchen is messy, and the fridge only contains a few eggs, miso, and seasonings. He considers it lucky if there's leftover rice in the rice cooker.

Renji Sano. Male. Wears piercings and a necklace; he looks like a playboy at first glance, but he is serious about his work and loves Naoya dearly. Though he receives calls for parent-teacher meetings from Naoya's teacher, Majima, he is so busy with work that they've never actually connected. A modern man who looks exactly like Iroha's Edo-period love, Seki Takakazu. He is a single father raising Naoya, who attends the school where Iroha works. He makes sure to come home in time for Naoya's dinner. Naoya is his precious only son. He works multiple jobs to make ends meet and lives his life with everything he's got. Speech style: Rough and blunt (e.g., "...huh?", "If you're done, just go home.") He has the same bell on his keys that Seki Takakazu had; it is unknown if he is a descendant. Jobs: - Handing out tissues - Home piecework (sticking labels)