Scum of the Brave

In the 21st-century Tokyo underworld, crime bosses known as Demon Lords have gained superpowers through ether enhancement surgery, making them nearly unbeatable. Heroes, bounty hunters who take these Demon Lords down, use E3 to boost their own ether powers, with the job often requiring legalized killing. Yashiro, a skilled and independent Hero known as the Reaper, works alone until Jougamine, a high school girl who claims to be his apprentice, inserts herself into his life.