Many isekai or time-loop stories use exactly this phrase or concept:

What is the nature of the 'hentai manga gaki ni modotte'? - WebNovel

The protagonist who travels back in time. He transitions from a victim of bullying to a calculated individual who uses his second chance for personal gain and revenge.

However, I need a bit more context to provide a precise response. The phrase seems to be a mix of informal and possibly misspelled or altered terms.

Includes characters like Saki , Yumeno , and Suzuhara , who were involved in Boku's childhood social circle. Adaptations and Availability

Adding kudasai (ください) makes it a request: Gaki ni modotte yarinaoshite kudasai. (Please go back to being a kid and redo it.)

It's a type of manga with potentially adult or explicit content. You might want to be cautious if you're not into such genres. Gaki ni Modotte Yarinaoshi!!! (2019) - aniSearch.com

Based on the title provided, this appears to be a reference to a "doujinshi" (fan-made comic) by the artist , likely titled or themed around "Modotte Yarinaoshi" (Return/Time Travel Redo).