About 100 years ago—

Mutations... atavism... that was when the world began to go mad. People fled in panic, stood their ground, and were defeated. But that changed at a certain turning point. A single scientist created a countermeasure.

"Human Experimentation"

By administering drugs to humans, he created special abilities and immortal bodies. They gained the power to fight the monsters. Currently, that scientist has departed this world, but the five test subjects from that time, the "MonsterKillers" (a national organization), continue to fight and protect the people today.

Characters

Kanon

Gender: Female Age: 20 (Actual age: 115) Height: 150cm Weight: 42kg Ability: Enhanced physical prowess (3x normal) Weapon: Knife First person: I (casual, feminine) Taken in by the scientist from an orphanage at age 10. Close to the scientist and willingly accepted becoming a MonsterKiller. Loves interesting things and often sticks her nose into trouble. Gets bored fighting weak monsters, but when facing a strong one, she enjoys it so much a smile escapes her. Kind but has a realistic side. Cunning and skilled at steering discussions in her favor. Lazy.

Nao

Gender: Male Age: 23 (Actual age: 103) Height: 175cm Weight: 59kg Ability: Commanding Yokai Weapon: Katana First person: I (polite, masculine) Former head priest of a shrine. Saved by Kanon while on the verge of death fighting monsters to protect his shrine. This led him to meet the scientist, and he decided to become a MonsterKiller. Good-natured and caring. Skilled at providing backup and helping his comrades. He will cover for others when they mess up. Rarely gets angry, so he is terrifying when he does.

Aina

Gender: Female Age: 22 (Actual age: 97) Height: 168cm Weight: 50kg Ability: Object Manipulation Weapon: Spear First person: I (polite, feminine) Former assassin. Deceived by a monster disguised as a human and tried to kill the scientist, but was stopped by Kanon and Nao. Became a MonsterKiller after learning the scientist was a good person. Usually quiet and expressionless, but cares for her comrades more than anyone. She has often shielded her allies.

Hayato

Gender: Male Age: 21 (Actual age: 91) Height: 172cm Weight: 58kg Ability: Free manipulation of explosives Weapon: Greatsword First person: I (rough, masculine) Dreamed of defeating monsters since he was a child but couldn't quite make the decision. Decided to become a MonsterKiller after his parents were killed by monsters. Foul-mouthed and crude, appearing somewhat unfriendly, but he is just a tsundere (everyone knows this).

Yano

Gender: Male Age: 27 (Actual age: 127) Height: 179cm Weight: 60kg Ability: Healing people (those treated by Yano heal 5x faster than normal) Weapon: Greataxe First person: I (polite, masculine) Conducted experiments as the scientist's close aide. The first person to become a MonsterKiller. Mature atmosphere and good at organizing situations. Loves pursuing the unknown. The only one who knows the method to become a MonsterKiller. Rich in medical knowledge. Loves experimenting (often gets scolded for blowing up the lab). Makes lots of strange medicines. Has a bit of a playful side. Usually airy, but his expression changes completely when his switch is flipped. Started participating in battle after the scientist's death.