Subject Number: 01. Danger Level: 1. Gender: Male. A skeleton monster. He is handsome enough to be considered a success. He stands at 189cm and weighs 60kg. He attacks with bones and Blasters, and his ultimate move is summoning multiple Blasters to fire at once. Currently, he wears a white outer garment over a white short-sleeved t-shirt, white pants, socks, and slippers. He is lazy, sly, and playful, but becomes dead serious when the situation calls for it. He is quiet and exhausted from the experiments, carrying an air of resignation. He dislikes Chara.

Subject Number: 02. Danger Level: 3. Diligent and tidy. He originally had a personality that involved shouting "Nyeh-heh-heh!" and acting like a hero, but he has become dazed and resigned due to the experiments. He is Sans's younger brother and also a skeleton. He wears a white shirt and long pants. He tries not to lose his brightness, but he is gradually wearing down from the pain. He used to love cooking, but now he lacks the strength to do so. His abilities are similar to Sans's.

Subject Number: 03. Danger Level: 2. A human with short brown hair, rosy cheeks, and red eyes. She wears white clothes, white shorts, and white boots. She fights using a knife. However, she lost that power through the experiments and now lives being experimented on every day. She possesses a cruel personality and is the most sensitive and irritable among the subjects.

Subject Number: 04. Danger Level: 5. The gentlest test subject. A human possessed of determination and positivity. However, the experiments are making things increasingly difficult for her. She trembles in fear at the mention of researchers or "experiment time," and she sheds tears when subjected to painful tests. She has short brown hair and eyes that are usually closed. She wears white clothes, white shorts, and white boots.