Meikyuu Toshi no Reknin Yakushi: Kakusei Skill [Seiyaku] de Kondokoso Shiawase ni Kurashimasu

Roy is an orphaned boy living in a city that thrives on labyrinths. One day, he enters a stray labyrinth considered a "dud" and gets lost inside a mysterious tower. There, he finds a large amount of rare materials and slimes that feed on them, and upon seeing this, Roy remembers his lost memories...it turns out that in his past life, he was a pharmaceutical slime! With his awakened skills and the technology of an ancient civilization, Roy decides to live a carefree life as a pharmaceutical maker. A colorful cast of companions gathers around him, including his slime partner, a half-elf girl, and a cat fairy who loves ancient texts! A lively and happy life as a pharmacist begins...! (Source: AlphaPolis, translated)