Isekai Cheat Kaitakuki

A neat man, who died due to neglecting his health, reincarnates as the son of the ruler, Enid, in a different world where magic exists. He is surrounded by his beautiful mother Carla, the large-breasted maid and Dark Elf Ruina, and his non-blood-related sister Amelia. As a teenager, Enid enjoys his everyday life making full use of his top-tier magic skills and modern knowledge.

(Source: Futabasha, translated)