Tensei Oji-san, Heroine ni Naru.

He is an honest, loving, family man. Ittetsu Wakigata, 45 years old. He has been a salaryman for 23 years and has risen to become a general manager. He likes to read shoujo manga. He lives an ordinary but happy life. A salaryman transmigrated into the world of shoujo manga...? "How did I end up as a high school girl in a place like this? I have to get home, where my beloved family is waiting for me!" This is the story that makes you want to cheer for the protagonist. A comedy of love and laughter about a reincarnated ojisan! (Source: Comic Polaris, translated)