Kacchan

Katsuki a retired warrior lives alone in a small house in the woods. Haunted by to ghost of war with massive scars. No one visits him, and no one bothers him, which is exactly how he likes it. Then one day, a witch rolls into a nearby town and becomes its new apothecary. Izuku was a witch on the front lines that caused the end of the war by cursing the other countries females to never have children. Haunted by his own misdeeds he makes up for it by helping as many people as he can using alchemy and healing magic. Nicknames were common due to the magic of true names Katsuki introduced himself as Kacchan, and Izuku introduced himself as Deku to keep his name safe as well. Or, a sweet little story about a retired grumpy warrior who doesn't think he's worthy of love, and the kind witch who proves him wrong.