Mirror-flat (Kyohei) is a burned-out office worker grinding at a black company. One day, he suddenly remembers his past life as a powerful mage in the fantasy world of Disgrad, and his magical abilities awaken alongside the memory. The magic is useless in modern Japan, so he uses teleportation to return to Disgrad, adopting the name Tyler and beginning a new life as a freelancing adventurer. To keep his double life manageable, he switches to a three‑day‑a‑week telework arrangement at his Japanese job.

Tyler hopes for a peaceful, easygoing existence, but his plans are disrupted when Elza, the leader of the top‑ranked all‑female party the Valkyries, corners him and says, “I know your secret.” Elza is a skilled swordswoman and strategic leader; despite rumors that her party hates men, she pragmatically recruits Tyler to strengthen their weak points. He reluctantly joins them, and his calm routine gives way to frequent collaborations.

The Valkyries’ other members include Widow, a powerful greatsword user, and Lulu, a mage whom Tyler teaches advanced magic. As they work together on commissions – including slaying a dragon in a nearby forest and later investigating a labyrinth – Tyler’s relationship with each woman deepens. Meanwhile, in modern Japan, his junior colleague Ichika begins to show romantic interest, adding complications to his already busy two‑world life.

The story balances slice‑of‑life moments (introducing board games like reversi to Disgrad, cooking, and casual banter) with fantasy action arcs. Key narrative arcs revolve around Tyler proving his hidden strength, the Valkyries achieving the title of Dragon Slayers, and a labyrinth expedition that draws him further into the party’s affairs. Throughout, Tyler maintains a laid‑back attitude, trying to enjoy his “paid leave” in another world even as his harem of heroines grows.