Kotaro Tatsumi, originally using the surname Inui during high school where he was Sakura Minamoto's classmate, adopted his current name likely as an entertainment alias after her 2008 death. He is the architect and producer behind the zombie idol group Franchouchou, resurrecting seven deceased girls from varied eras to save Saga Prefecture from a prophesied curse threatening its existence. His goal, tied to the bartender Jofuku's plan, involves revitalizing Saga through the group's popularity, though its full scope remains mysterious. His appearance features pale skin, neatly combed brown hair swept to the right, and dark sunglasses perpetually concealing his eyes. He typically wears a white shirt with a dark blue bow, a red vest displaying a dried squid tentacle, and a navy-blue jacket draped over his shoulders. During a depressed phase in the second season, his hair grew long and unkempt over his face, accompanied by a beard and sloppy clothing. High school flashbacks show him in a black gakuran military uniform. Kotaro exhibits a loud, eccentric, and seemingly arrogant persona as an idol producer, often dismissing common sense to achieve his goals. This masks a deeply insecure, anguished, and reserved individual struggling with public expression, frequently doubting his plans, leading to stress-induced physical ailments and depressive episodes. He shows genuine vulnerability during failures, such as isolating himself and drinking heavily after Franchouchou's disastrous Ekimae Fudosan Stadium concert left the group in massive debt. Despite flaws, he demonstrates professionalism in managing opportunities and offers pivotal guidance, like advising Junko to embrace her own idol identity and warning Saki about endangering the group. His development progresses from an impulsive, harsh manager prioritizing rapid success over the girls' well-being – exemplified by forcing Sakura to perform at a death metal venue against her objections – to a more responsible and supportive producer. After the EFS failure, he reflects on mistakes and becomes kinder, making decisions focused on group growth, such as temporarily excluding Ai from an Iron Frill collaboration to foster independence in the other members. His relationship with Sakura notably improves, culminating in a heartfelt promise to support Franchouchou's dream of global recognition. Kotaro possesses multifaceted abilities: songwriting, crafting songs tailored to the girls' dynamics and drawing inspiration from sources like tofu or local cuisine, such as the duet "Atsuku Nare" for Ai and Junko; proficient beatboxing during rap battles and rapping ability; makeup artistry skillfully concealing the zombies' decay; and necromancy, having resurrected the seven girls and his pet zombie dog Romero, though the methods remain unexplained. As Franchouchou's producer, Kotaro handles logistics, secures sponsorships, and organizes performances while navigating crises like public exposure risks. His actions are driven by a literal mission to prevent Saga's destruction, culminating in Franchouchou uniting the community during a catastrophic storm. The saga concludes ambiguously when a UFO seemingly annihilates the prefecture post-storm.