Sena Satou, who works as a medicinal researcher, finds herself lost in a different world - and she is not the only one! One day, after managing to start life as the medicine man 'Sena', she encounters a mysterious man. He is the demon king Delmatitidis, a man of immense beauty and strong magical powers, but sickly and weak. Sena's knowledge and experience in herbal medicine is recognised, and she becomes his personal apothecary, with whom he shares a special and unforgettable time. And so, before long, the two are drawn to each other. A drowning romance that will change the destiny of a genius former Licejo apothecary and a beautiful Demon King begins!