Attack on Titan: No Regrets

Shingeki no Kyojin Gaiden: Kuinaki Sentaku Prologue (Attack on Titan Side Story: A Choice with No Regrets Prologue) is an ongoing spinoff manga illustrated by Hikaru Suruga and written by Gan Sunaaku. this manga focuses on Levi, and the The events happening in it are prequel to the series. There's currently one single prologue chapter published, with the first chapter coming in the next issue of Aria.