The series started off kind of interesting, but the plot has no real direction. There's no character growth or development (beyond the main character being OP), and the plot gets pretty nonsensical in the middle, with events happening with little setup or payoff.
I mean, normally there's a power curve to these things, unless it's One Punch Man, where Saitama being insanely OP is the whole point. But this does has an oni invasion and oni god encounter before they fight a bunch of assassins and random human bandits. WTF?