World-renowned scientist Dr. Dalton Wyatt is unexpectedly transmigrated into the body of his namesake, a high‑school student who recently committed suicide. He awakens in a harsh new world where humanity battles relentless dungeons and monsters, and only a select few—known as Card Apprentices—can wield grimoire‑bound cards to survive. Armed with his Earth‑side knowledge of science and invention, Dalton quickly discovers that the key to power lies in card creation and fusion, allowing him to craft perfect, high‑grade cards from seemingly worthless ingredients. Using his unique expertise, Dalton turns card crafting into a lucrative trade, selling powerful items to earn money and climb the ranks of this monster‑infested realm. As he navigates political intrigue, harem entanglements, and the ever‑present threat of stronger foes, he must balance his scientific mindset with the mystical rules of the grimoire system, all while uncovering the deeper mysteries behind the world’s reliance on cards instead of technology.