Oshi ga Shinushi Tasukerushi

Yuko is a full-time housewife living with her husband. In her stressful days, her only purpose in life is to support her favorite idol, Hoshino-kun. ...But then... one day, news breaks that Hoshino-kun has died from acute stimulant drug poisoning. In despair, Yuko chases after an afterimage of Hoshino-kun and ends up in an accident. When she wakes up, she finds herself in a new world where Hoshino-kun was a child actor...!? A time-traveling love story that begins with the death of her favorite idol!

(Source: Hakusensha, translated)