Maou is everything.  Techniques are strength. Evolution is power. Chisson has none of these. He has done everything he's supposed to, but his maou simply doesn't work - and it doesn't seem like it ever will.  When a stranger appears and offers him a solution, circumstances push Chisson to take the ridiculous offer, leading him down a path to decide the direction of a world where maou itself is transforming. Chisson must evolve to keep up with it. Change is the only possible way forward.