Clantail, whose real name is Nene Ono, is a central protagonist in the second arc of the story. She is a middle school girl who appears younger than her age, being so short that she could be mistaken for an elementary school student. In her human form, she has a plain appearance characterized by twin braids and unfashionable black plastic glasses which she needs to see clearly. As a magical girl, her appearance changes to feature short brown hair with purple flower designs floating above it, red and yellow eyes, and a low-cut outfit in purple, pink, and beige tones. Most notably, the lower half of her body is transformed into that of an animal, most often a deer, reflecting the nature of her magical abilities.

Clantail's magic allows her to transform the part of her body below her waist into various animals. This ability is highly versatile and she uses it to adapt to many different combat and travel situations. She can change her lower half into a horse or deer for swift movement on land, a dolphin for swimming, a spider for traversing wetlands and using thread to capture opponents, a gecko to stick to walls and ceilings, a jellyfish to extinguish fires, and a moth for flight, among many others. The transformations follow specific rules: if she transforms into a creature that is normally small, its size adjusts to fit her human upper body, but if she transforms into a large creature, she gains the animal's full size. She can only transform into animals she has seen in real life and must recognize them as such. In a notable instance of creative application, she partially transforms into a Great Dragon, a creature that exists within the game world, to deliver a decisive blow against a powerful enemy. Her fighting style is direct and formidable, making her one of the strongest combatants in her team.

Despite her powerful abilities, Clantail struggles significantly with social interaction. She has a calm and stern demeanor and rarely displays emotion, which leads others to perceive her as cold or unfeeling. In truth, she simply does not know how to relate to people. She has difficulty reading between the lines, remembering faces, and understanding the mindsets of others, which often results in unintended offense. She finds animals much easier to understand than humans, and her love for them is the source of her magic. Her dream is to become a zoologist. Interestingly, while her face rarely shows emotion, her feelings can be easily discerned by observing the movements of her animal half, such as a tail wagging in enjoyment. She acts as the levelheaded leader of her team, mediating conflicts between the argumentative Rionetta and Nonako Miyokata, and consistently shows consideration for all her teammates, including the less capable Pechka.

Clantail's role in the story is that of a primary protagonist and team leader who is determined to protect those under her care. She acts as a stabilizing and responsible presence, focusing on completing their objectives while keeping her group cohesive. Her motivations are rooted in a strong sense of duty towards her teammates and a deep-seated aversion to seeing others die. The traumatic events she endures, specifically the deaths of her teammates, leave a permanent mark on her. She suffers a Heroic BSoD after these losses, and the experience instills in her a powerful Chronic Hero Syndrome, compelling her to try and save anyone in danger, even former enemies or strangers. This trauma also drives her to become extremely prepared for any future crisis. In a later story arc, it is revealed she has trained her human form in survival skills and brought supplies to a crisis zone, actions considered paranoid but which prove beneficial when the magical girls are forcibly detransformed.

Her key relationships are largely defined by her role as a protector and friend. With her teammate Pechka, Clantail is kind and appreciative, communicating approval through subtle actions rather than words. Pechka respects her as a leader, and her sacrifice to save Clantail is a pivotal moment that she cherishes forever. With Rionetta and Nonako Miyokata, she acts as a mediator and a respected leader whose orders they follow. Following the deadly game, she forms a close friendship with the other survivors, Pfle and Shadow Gale. Shadow Gale often stays at Clantail's house to escape Pfle's troublesome personality, and Clantail is content to have her as a friend. She also assists Pfle with various tasks in later stories. Later, she accompanies Ragi Jie Nent on an investigation, prioritizing his safety, though she ultimately cuts off contact with him after disagreeing with his rigid adherence to rules over helping others.

Clantail undergoes notable development as a result of her harrowing experiences. Before the events of the story, she was socially isolated and struggled to connect with people. After the game, she makes a conscious decision to become more sociable, learning to cook and interact more with her classmates. She specifically vows to learn cooking to honor Pechka's memory by making her favorite foods. Her trauma also shapes her into a more proactive and prepared individual, determined never to be helpless to save others again. She transitions from a withdrawn girl who preferred the company of animals to someone who actively works to build human connections while carrying the weight of her past losses.