i forgot the name of a manga with a similar plot to dgrayman. It had a main character that could change their arms into weapons and various cities cities ranked by importance. It also had a evil organization and one hunting the evil one that either kills or turns them into monsters. Each huunter also had a suppivisor watching them waiting to kill them if they became monsters.

Found it

https://www.mangaupdates.com/series.html?id=113170