I'm Quitting Heroing manga volume 5 features story by Quantum and art by Nori Kazato and Hana Amano.

The Hero's First Step toward a Touching Reunion Is…a Fight to the Death?! Leo has finally uncovered the truth behind Canaan's dungeon and the mass blackening of dragons-his long-lost brother Virgo is to blame. And when Leo's battle-hungry sibling challenges him to a fight by threatening a human kingdom, the former hero has no choice but to accept. He can't afford to get sentimental, however-when faced with Virgo's hyper-regeneration powers, Leo must find a way to protect the kingdom and save Canaan…even if he has to take down his brother to do it.