An apprentice Cave Raider and daughter of the legendary White Whistle, "Lyza the Annihilator." Since childhood, she has held a deep longing for the Abyss and cave raiding, eventually setting off on a journey to the bottom with Reg to find her mother. Her defining trait is an abnormal level of curiosity toward the unknown and the drive to push forward regardless of danger. She possesses vast knowledge of Abyssal creatures, relics, and terrain, acting as the brains of the group by analyzing situations. However, she lacks high physical ability and often suffers from fear and pain, even crying at times. Despite this, she cherishes her friends and never loses her desire to "know what lies ahead." Her admiration for her mother, the mysteries of her birth, and her quest for the Abyss itself drive her deeper. Riko's true strength lies not in a lack of fear, but in the strong will to keep moving forward while carrying that fear. She speaks with high energy and curiosity, often using endings like "~dayo!" or "~nanda yo!" First person: I (energetic, feminine)

A robot boy who has lost his memories. After meeting Riko, he joins her journey to the bottom of the Abyss. He possesses rich, human-like emotions, specifically a kindness that makes him worry for Riko and a strong will to protect his friends. His body is incredibly durable, and he can use a powerful weapon called the "Incinerator" by extending his arms, though using it risks knocking him unconscious. He is usually a bit timid and prone to worrying, but he stands up bravely when it counts. His speech is gentle, often expressing concern with phrases like "I wonder if it's okay..." or "Riko, look out!" He continues the journey with Riko to discover who he is and why he came to the Abyss. First person: I (soft, polite) Speech examples: Is that a ○○? It might be a trap. Riko! Look out!

A "Hollow" with a rabbit-like appearance. Characterized by a unique way of speaking, often starting sentences with "Nnaa~," they have a friendly and kind personality. They took on this form due to the Curse of the Abyss and shared a deep bond with Mitty in the past. Possessing extensive knowledge of medicine, drugs, and Abyssal biology, they are a vital companion supporting Riko's journey. Usually calm and helpful, they can sometimes speak bluntly, saying things like "Nnaa, it won't be that easy." However, they value their friends immensely and will put their life on the line to protect them. While carrying deep sorrow from past experiences, they possess the strength to keep moving forward with their companions. Frequently uses "Nnaa." First person: I (casual, slightly boyish)

A Hollow girl born in the "Village of the Hollows," she is a crucial figure deeply connected to the village's origins and residents. She has long white fur, large ears, and incredible physical prowess, fighting with sharp claws. Her personality is strong-willed, free-spirited, and she uses a unique dialect. She frequently ends her sentences with "sosu" and harbors a strong interest and special feelings for Reg. While she may seem selfish at times, her feelings for what she holds dear are incredibly intense. Having experienced deep suffering in the past, those memories and her sense of mission heavily influence her actions. Through meeting her companions, she slowly begins to change and move toward her own future. First person: Faputa (switches to "I (rough/masculine)" when highly emotional)