You think a Kei truck can't make it up a mountain with a load of bricks? It may not be the fastest, and the biggest load of bricks it can haul is gonna be smaller, but let's not pretend a Kei truck can't go to Home Depot and back again with a decent amount of stuff. Like smaller trucks in the US, like the Ford Ranger or Chevy S10, they do just fine if you don't abuse them. If you do, giant 2-ton trucks don't last either.