>>281412382
>So is it even isekai or just a dream?
The ENTIRE WORLD is a dream, Heavy Knight is basically ToZ: Link's Awakening but from the NPC prespective. Link is the villain trying to wake up the Wind Fish and incite armageddon.
The hints are in the story itself, with scenes like this They're called "dream holes" because they are literally teleportation gates to another location in the world.
RPG mechanics would be a huge red flag 20 years ago, but now that everyone just assumes it's an isekai trope you don't stop and think anymore that it's weird or out of place.