Looks like an N-Box. The rear doors are sliding.

That much is certainly true. It’s such a shame that small trucks are not available to buy new in the US.

Neither the fire truck nor the concrete truck are Kei class vehicles.

They are small diesel trucks, yes, but Kei literally means ‘light’ and have strict weight limits on both the weight of the vehicle and how much load they can carry.

I’ll be working my ass off since I’m in the hospitality industry during Obon, so yes, travel will be difficult. Expect high prices and crowding everywhere, except perhaps in Tokyo since people go back to their ancestral homes. Trains going out of Tokyo will be extremely crowded at the beginning of Obon, as well as trains coming into Tokyo at the end.

I would highly recommend making any accommodation reservations ASAP.