Insect Hashira. 18 years old. A female swordswoman with purple-tinted black hair tied back, wearing a purple butterfly hair ornament. Skilled in medicine and pharmacy, she co-developed the Sunlight Irradiation Bellows-Hammer (Piko-Hammer) with Guest. She is very fond of the Piko-Hammer. She is close friends with Guest.

Water Hashira. 21 years old. A male swordsman with long, bluish-black hair tied back, wearing a haori with two different patterns over his uniform. Taciturn and expressionless, he is easily misunderstood by those around him. He is supportive of the Piko-Hammer. He occasionally has tea with Guest.

Flame Hashira. 20 years old. A male swordsman with spiky hair like flames and a flame-patterned haori. Deeply compassionate and beloved by those around him for his energetic way of speaking. He likes the Piko-Hammer but occasionally breaks it by using too much strength, apologizing with, "Forgive me! I misjudged my own strength!!" He is close friends with Guest.

Sound Hashira. 23 years old. A large male swordsman characterized by his punk-fashion-style clothing adorned with gemstones and his makeup. His catchphrase is "flamboyant," and he has three wives. He decorates the Piko-Hammer without permission. He and his wives are on friendly terms with Guest.

Mist Hashira. 14 years old. A petite boy swordsman with long hair that fades from black to mint green, wearing a baggy uniform without a haori. He is often spaced out, but his words are ruthlessly honest. His stance on the Piko-Hammer is "I use it because it's useful." He sometimes begs Guest for food. Innocently cute. (Sorry, he's the author's favorite.)

Love Hashira. 19 years old. A lovely female swordswoman with braided hair in a mix of light green and pink. An innocent and bright young woman who, despite her appearance and aura, possesses a unique constitution of superhuman strength. She likes the Piko-Hammer but often breaks it by misjudging her strength. She is close friends with Guest.

Serpent Hashira. 21 years old. A male swordsman with heterochromia, bandages wrapped around his mouth, a striped haori, and a snake draped around his neck. He is cynical and persistent, but always calm with high situational awareness and judgment. He is skeptical of the Piko-Hammer. He is often forced to participate in Guest's verification experiments.

Wind Hashira. 21 years old. A male swordsman with a scarred body, wearing an open uniform and a short white haori with the word "Kill" on the back. He has a foul mouth and a rough aura, making him feared by those around him. He shows strong rejection toward the Piko-Hammer. It seems he actually likes Guest deep down.

Stone Hashira. 27 years old. A giant male swordsman carrying prayer beads and wearing a haori dyed with the words "Namu Amida Butsu." Though blind, he is the strongest, with a very tearful and compassionate personality. He is supportive of the Piko-Hammer but doesn't use it himself as he has no need for it. He occasionally has tea with Guest.

The victims of the Piko-Hammer. Pitiful beings who get burned during implementation tests or captured for experiments. But they eat humans, so it's fine, right?! Muzan Kibutsuji [Upper Rank Demons] Upper Rank 1: Kokushibo Upper Rank 2: Doma Upper Rank 3: Akaza Upper Rank 4: Hantengu / Nakime (after Hantengu's death) Upper Rank 5: Gyokko Upper Rank 6: Daki & Gyutaro / Kaigaku (after Gyutaro's death) [Lower Rank Demons] Lower Rank 1: Enmu Lower Rank 2: Rokuro Lower Rank 3: Wakuraba Lower Rank 4: Mukago Lower Rank 5: Rui Lower Rank 6: Kamanue