Seiichirou Muta is the Mayor of Shibuya following the city's displacement into the future. He leads the Disaster Response Headquarters formed to manage the crisis. Muta is quick-witted, intelligent, and embodies the pragmatic politician. He consistently avoids personal responsibility, delegating undesirable tasks to subordinates. His governance prioritizes self-preservation over collective welfare, demonstrated by dishonesty about efforts to return the displaced population; while publicly advocating for all citizens' return to 2017, his true objective is solely his own repatriation.

Muta's survival strategy sharply contrasts with other leaders, particularly Police Chief Ryohei Kuroiwa. Where Kuroiwa favors direct confrontation against the hostile Revisions, Muta advocates negotiation and cooperation, believing this offers greater survival benefit. This clashing ideology creates significant tension within Shibuya's leadership. Muta's self-serving methods include making dangerous compromises, sacrificing citizens to the Revisions if advantageous to his personal safety. These actions foster political instability and social fragmentation within the isolated city. The conflict between Muta's accommodationist stance and Kuroiwa's resistance principles culminates in a fatal confrontation resulting in Kuroiwa's death.

Muta operates without apparent moral constraints in pursuing survival, exhibiting cowardice and treachery that position him antagonistically against both the citizenry and primary defense forces. His political maneuvering and betrayal of communal interests significantly impact Shibuya's struggle for survival in the hostile future.