Weeb_Polleke said:i don't think there was huge timeskip (maybe a few months), but i agree it's a bit complicated. i'll try to explain clearly. [SPOILER ALERT!]
in s1 the story ended with an overall happy ending. The ''war'' between heroes and demons was settled by Anos and the transfer student hero guy (who was secrectly the new demon lord). And so there was some kind of peace between them.
This s2 probably has nothing to do with s1. the story of s1 has ended and the story of s2 started with a random angel/god dude that said 'yo, 1 of the students is the chosen 1 for a project so we gonna take him/her'.
So to finish up, s2 is just a new story with new bad-guys and new secrets.
the main story of s2 is about:
'who is that special student'
'who are the bad-guys and what is their plan'