
2nd season of its anime went with different route like Spider survived in 2nd season but in manga died. So that's why its anime can be confusing so go for manga tho it updates monthly and slowly translated rip

You do realize that the manga is the original and the anime is adapted right? It's not the manga that follows but the anime that follows but likes to change things. Not everyone/thing lives. Having everyone live isn't always good writing. This story in particular isn't one of those "everyone lives" and shouldn't be one. Apdated animes does that a lot in which those who should die don't die. It gives the character who killed it or who is killed more depth depending on how much they affect the story.
I thought the girl was dense but devil turned out much more Dense
( ̄へ ̄)
Well, they say devils can't fall in love so it's probably not even on his list of possibilities.