[Demon Slayer Crossover] What's Your Problem, Sun Breather?

☆ Blurb ☆ A retired Water Hashira takes in an orphan, planning to train him as his stepson. But then Alaya whisks the kid off to Chaldea, and when he comes back, he's got a cheat mode switched on. "Sorry, Master. I might have to become a Sun Breathing successor." The master, who'd been about to have a perfectly good stepson and suddenly doesn't: ? The former Sun Hashira of the Demon Slayer Corps, who died four hundred years ago: ? A certain famous, anonymous Sun Breathing PTSD sufferer: ? "Sun Breathing... isn't a reason for you to torment me..." "I'm not tormenting you. I just want your body, and I'm being honest." "...???" "Have you heard? The Demon Slayer Corps received a complaint from one of the Twelve Kizuki!" "It says... the Water Hashira should spend less time with his Sun Breathing successor, so he doesn't make him stupid?" "...?" The Water Hashira is still very confused today. * ☆ Reading Guide ☆ 1. The pairing is set: 1v1, with the younger one pursuing the older one. 2. This idea is on the back burner. I'll start writing once the pre-collection reaches 400, or whenever I feel like it. √ Theme: "