Masotan, an Organic Transformed Flyer (OTF), is a dragon-like entity secretly housed within the Japan Air Self-Defense Force's Gifu Air Base. Classified as a "Metamorphosed Flight Organism," he avoids public detection by mimicking an F-15J fighter jet using specialized armor. His physical form features a large, robust body with disproportionately small forelimbs compared to his hind legs, yellow markings around the neck, tail, and wings, antennae, and gill-like frills along his head—traits enabling aircraft resemblance even without armor. His eyes display distinctive black sclerae with white irises during pilot swallowing or regurgitation. Before bonding with primary pilot Hisone Amakasu, Masotan remained inactive and irritable for three years, rejecting all potential candidates. His personality merges serenity and laziness with skittishness and stubbornness, often refusing flights under unsuitable conditions or with incompatible pilots. Despite intimidating newcomers with his size, he exhibits deep compassion and protectiveness toward his pilots, sometimes overriding their decisions if he deems them unwise. Operationally, Masotan physically swallows his pilot, who navigates via a holographic control system within his stomach; pilots wear acid-resistant suits for protection. A biological restriction called "anastomosis" severs the bond if the pilot develops romantic feelings for another person, triggering violent rejection. Past bonds include Moriyama (callsign "Forest"), whom he rejected after she fell in love and became pregnant, and Sada Hinomoto (callsign "Montparnasse"), who flew him during the Ritual 74 years earlier. Sada retired after her partner Yae was sacrificed to the giant OTF Mitatsu. Hisone initially nicknamed him "Otofu" (a play on "OTF") but discovered his true name engraved internally. He displays a fear of strangers and consumes flip phones to ingest rare metals. During the central Ritual—a recurring event to guide the colossal Mitatsu-sama to a new resting place—Masotan disobeys orders to rescue Hisone from being chosen as a sacrificial offering, demonstrating his fierce loyalty and prioritization of her safety over protocol.