When Young K’s too lazy to move, he’s imagine teleporting, but not just the sudden teleportation, he’d imagine stuff like, what if there’s an object directly where he teleports, does the thing disappear then he appears? or does the object combine with him?
so the way I see it, the story they're trying to tell is about growing up their High School days in Dear H, to future horizons they face in Good Enough
and for some reason, Junhan isn't there with them in the future timeline, but somehow he's the one keeping them together+