this story primarily focuses on the two characters. Jeanne and Mael. the author literally writes about his undying love towards Jeanne. this story is boring. as simple as that. the author finds aspects that usually makes novels interesting to not be worth writing. Particularly on a family's overall situation (in terms of finance, home, settlement, jobs, etc), their training (like tell me more than just him doing saitamas training plan; he literally became a knight, but how?), the social interaction, and your time skips are just so dull, the main reason why Jeanne fights is about the war between Britain and France yet all these time skips and you don't explain the overall situation. there's also only interaction between mael and Jeanne, that's why I find it so boring, side characters make some of the best novels interesting.
the world background, bruh you only talk about Britain and France, as for character development, I don't see any; the man literally adores Jeanne and that's why he transmigrated, so I don't see any progress there.
people saying this dxd fanfic is good must have pretty low standards, but hey who am I kidding this is Webnovel
