Mafuteru Rei's Manga

A failed idol becomes a successful actor in adulthood, but suddenly dies now he's back as a kid where his parents are still together and becomes a famous child actor

Mc failed to debut as an idol as he couldn’t secure a spot in a survival show and now works many sidejobs after it. The group he was supposed to debut in had too many controversial scandal eventually leading to downfall. Mc meets one of the members and fights, mc gets hit by a truck and is suddenly back to the past.