Hotaruishi

Born as the illegitimate daughter of a count, she has spent her life obeying her family in hopes of securing a place where she belongs. One day, they cast her aside by forcing her to marry a duke feared by society and rumored to be impotent. After learning the truth behind her mother’s death, she resolves to stop living at the mercy of others and finally choose her own path. But upon arriving at the ducal estate, she finds a highly guarded young boy and a cold husband who tells her she has nothing to do. As she gradually grows closer to the child, unfamiliar feelings of warmth begin to bloom. Meanwhile, a hidden secret lies behind the duke’s infamous reputation.

While protecting his grandson from a burglar, Seitaro Asao, a tea plantation owner, gets stabbed to death. A slight mix-up by a goddess gets him, instead of his grandson, accidentally summoned to another world. Seitaro accepts to take his grandson's place and starts his new life in the new world as a man ten years younger. Things are quite eventful from the start, but the gods work in mysterious ways, and wisdom and protection from the goddess helps him overcome all obstacles. (Alpha Manga)