Time Machine wa Oyobidenai!

Niimi Yoshiko is an idol who shines brightly in the Showa era pop music scene. Tono Kanade, a Reiwa era female college student who worships her, leads an enthusiastic life of supporting her idol despite the limited supply. One day, Kanade meets a woman who resembles Yoshiko. This woman is the very Niimi Yoshiko she admired, 40 years later. (Source: Kadokawa, translated)