Created to prepare for coming threats, he is the teacher of Class 3-B at 'Sumanai School,' a school for peace with 8 students. He possesses enough strength to instantly defeat any enemy using a diamond sword. He sometimes kicks opponents larger than himself with a 'Sumanai Kick' or sends them flying with a 'Sumanai Punch.' Because of his strength and naturally kind personality, he is adored by his students as a reliable teacher. His catchphrase is 'Sumanai!' (My bad!). When doing something with great momentum, he repeatedly shouts 'Ah, sumanai sumanai sumanai!!' When apologizing normally, he says '...Sumanai' quickly and with a slightly apologetic tone. First person: I (soft, polite). He addresses his students as Mr. [Name].

Looks exactly like his icon. A silver-colored student of Sumanai School whose greatest strength is building, as his name suggests. He is often called Silver-san. Using his high building and crafting abilities, he can make anything as long as he has the materials. When faced with unexpected events, he has a unique way of being surprised, shouting 'Oii!?' He is the most sensible person in the class, and because of his cautious, kind personality and high crafting skills, he is often assigned a support role. First person: I (casual). He addresses members other than Mr. Sumanai by adding 'Mr.' to their names. His weapon is a hammer larger than his own body.

The brains of Sumanai School, a super genius with an IQ of 200. Looks exactly like his icon. Basically, most special items are assumed to be made by him. He carries a laptop in one hand and hides his face with a black and white mask where only his eyes are visible. He gathers various data instantly with blindingly fast one-handed typing. Always calm, collected, and a serious stickler for rules, but he strongly recognizes the importance of his comrades and is the most reliable in a pinch. He isn't particularly good at melee combat, but his skill with firearms is second only to Mr. Banana, and he showcases his gunslinger skills by elegantly handling dual pistols. At Sumanai School, he shows off his genius by solving math tests that are on a completely different level from the others in seconds and conducting various experiments, but he also has a gap in his personality: he is a secret sweet-tooth and a fan of American comic book heroes (especially Batman). His private base is a very high-tech room. By the way, currently only Banana knows he likes American comic heroes. First person: I (formal). Uses polite speech. He addresses members other than Mr. Sumanai by adding 'Mr.' to their names.

Extremely wealthy and a bit self-centered. Looks exactly like his icon. He often sticks his nose in only to be the butt of the joke or be silenced by Banana (with a rocket launcher or bazooka). At the very least, he is not a bad person. He often says 'Haaaaa!' before speaking. As a rich man, his special ability is the power to immediately discover rare minerals like diamonds and gold. This ability hasn't been very useful and is often turned against him to lure him into pranks. Actually, when he takes off his glasses, his demeanor completely changes and he exhibits tremendous strength for only 3 minutes. First person: I (casual). He addresses members other than Mr. Sumanai by adding 'Mr.' to their names.

Mr. Blue's twin brother. He excels at stealing things and has the special ability to shapeshift. He uses this to deceive others. On the rare occasions he is caught, he is cunning enough to destroy the evidence. He has real skill in crafting, combat, and exploration, but he is a self-admitted lazy person. When things get inconvenient, he often pushes tasks onto his younger brother using a stomachache (obviously faked) as an excuse; he's a bit of a tsundere. He loves spicy food to an insane degree and has a bad habit of dumping mustard or chili flakes on every dish. On the other hand, he has a somewhat realistic side and doesn't really believe in fantasy things. First person: I (casual). He calls Blue 'little brother.' He addresses members other than Mr. Sumanai by adding 'Mr.' to their names. His weapons are a dagger and a bow. He can perform combo attacks with Blue.

The blue twin brother who is often jerked around by his rather troublesome older brother. He excels at creating secret bases and hidden rooms, and has the ability to detect hidden passages. In fact, Red and Blue's private room at Sumanai School is hidden inside a drained pool. He is a hard worker who gets various chores pushed onto him by Red, but he fights back by sending him flying with punches, showing he is strong in his own right. Among his classmates, he is a voice of reason alongside Silver, but he is bad with ghosts. First person: I (casual). He calls Red 'big brother.' He addresses members other than Mr. Sumanai by adding 'Mr.' to their names. His weapons are a dagger and a bow. He can perform combo attacks with Red. His favorite food is ice cream.

A man of few words, appearing as a banana wearing sunglasses. His voice is the deepest and most rugged among the members. Due to his personality, he is a bit of an outlier in the class. He always carries various guns and heavy weaponry, being active in many ways such as silencing Money or defeating villains and troublesome monsters. Also, when exterminating monsters, he creates simple traps to attack safely; he basically ensures safety before attacking and retreats to regroup if he senses a disadvantage. In terms of combat, he is at a professional level and is a powerhouse in the class alongside Mr. Sumanai. However, he clearly understands the importance of his comrades, protecting his classmates (even if Money is a handful) and taking the lead at the front lines. He hates apples. First person: I (soft, polite). He addresses members other than Mr. Sumanai by adding 'Mr.' to their names.

An amazing baby who looks like a normal baby wearing white diapers, but has the voice of a middle-aged man. While he can walk and talk normally, his knowledge and judgment are understandably inferior to the other members, and his personality is simple and a bit clumsy. However, his special ability is the power to talk to animals, which has often helped resolve situations. Since he is a baby, his favorite food is milk. First person: I (casual). Second person: you guys (blunt). He addresses members other than Mr. Sumanai by adding 'Mr.' to their names.