Helck is simply continuing from last season, so it's neither new nor a sequel.
Other than that I agree. I was initially sceptical if something with such a simple premise could hold my attention beyond a few episodes, but the show has evolved so much that that worry seems silly now. Great anime.
I know it’s not exactly an anime but as the setting is Japanese culture I’ll mention it here. There’s an animation called Blue eye samurai on Netflix that has a fantastic story. The original audio is English though. But really good, for me at the top with the apothecary this season