The Master operates Western Restaurant Nekoya, an interdimensional culinary haven bridging Tokyo and a fantastical realm. Inherited from his grandfather Daiki Yamagata—co-founder with Koyomi Yamagata, a warrior from the other world and member of the Four Heroes—he retains a key gifted by Koyomi to sever the restaurant’s interdimensional ties, yet upholds its legacy. Trained under Daiki, he assumed ownership a decade ago, mastering a repertoire of dishes that draw elves, demons, dragons, and deities to his tables.

Every seventh day, Nekoya’s doors manifest in the other world where sustenance or solace is needed, guarded by dragon deities Red Queen and Kuro to preserve neutrality. Patrons must obey non-violence and payment rules; violations trigger the restaurant’s own retribution, such as irreversible banishment. This policy transforms Nekoya into a sanctuary where adversaries dine side-by-side, forging unlikely alliances over shared meals.

Unaware of his childhood barter with Emperor Wilhelm—exchanging potatoes that averted a famine—the Master’s quiet influence extends beyond cuisine. He employs ostracized demon server Aletta and Kuro, who assumes human guise, blending pragmatism with empathy. Ingredients sourced from Tokyo suppliers, some privy to Nekoya’s secret, fuel innovations like curry rice and beef stew, reshaping the other world’s culinary landscape despite their inability to replicate his techniques.

Koyomi occasionally visits, observing her grandson’s stewardship as the restaurant sparks diplomatic truces, cultural fusions, and personal revelations: a merchant-princess reconciliation, a shipwrecked admiral’s solace. The Master remains a neutral figure, channeling efforts solely into cuisine, abstaining from otherworldly conflicts beyond nourishing their participants.