Kyouhei Tachibana is an eighteen-year-old student at a culinary arts school who serves as the cook for a group of young mercenary women. His primary goal in life is to become a patissier, a professional pastry chef, and he dreams of traveling to France to further his studies. To afford this ambition, he takes a part-time job responding to a want ad for a private chef, not knowing that his employers are the highly capable and violent mercenaries Jo, Meg, Amy, and Sei.

In contrast to the action-oriented world he is thrust into, Kyouhei is a non-action oriented civilian who has never experienced violence before. He is often described as a coward and reacts to dangerous situations with fear and reluctance, a justified response given his background. His primary value to the team is his exceptional talent in the kitchen, where he is proficient in a variety of cooking styles, including Chinese, Italian, and Japanese cuisine. He provides a grounded, normal perspective amidst the chaos of the team's missions. Despite being a central character in the series' premise, Kyouhei receives little significant screen time as the story progresses, and his role largely remains that of the team chef, not a combatant. He has a crush on a classmate named Shiho Kazami. Over the course of the narrative, he experiences minimal character development, and his function does not evolve beyond preparing meals for the group. His most notable abilities are entirely culinary; he is a gifted cook capable of creating a wide variety of dishes, which serves as his main contribution to the mercenary team he unwillingly works for.