Watashi no Kokoro wa Oji-san de AruMy Heart Is an Old Man; 私の心はおじさんである（コミック）; This Alluring Dark Elf has the Heart of a Middle-Aged Man!; My Heart is an Ojisan

"Haruka Yamagishi" is a guy who has no friends or family and just goes back and forth between work and home. One day, when he wakes up, he finds himself in a different world. And for some reason, he's turned into a beautiful dark elf! Now, Haruka has inexhaustible magic power, a sturdy body, and a new life where she can do anything... However, through the friends she met and her activities as an adventurer, changes slowly began to take place. The guy who gave up on life in this world begins to feel what it's like to live. Although there are some traps and other events, it's a touching adventure story![Source: Manga updates]