Yawaraka-sensha ("soft-tank") videos are all over YouTube; a good place to start is the first one, in which we see several of the eponymous tanks mistreated by small animals, bacteria, etc. Homepage, interview:

But why tanks?

People say "marshmallow-soft", but that doesn't cut it for me. This is because I believe that soldiers on the battlefield are softer by far than any marshmallow.

I think if you've seen Saving Private Ryan you'll know what I'm talking about, but that first scene, with bullets flying everywhere, all those soldiers totally exposed and suddenly getting riddled with holes -- I saw that, and thought "Man, soldiers are soft!".

Pistols and knives only work as threats because humans are so soft. Seems like most people have a complex about this their whole lives. Well, maybe not [Korean-born karate legend] Ōyama Masutatsu, but you get the idea.

On the other hand, tanks are just unbelievably hard. If your doorbell rang and you opened the genkan door and saw a Type 90 there all like, "Hello! I'm from NHK," you'd shut up and pay your fee, right? Because you can't fight a tank. Well, maybe Ōyama Masutatsu wouldn't pay, but you know.

And so it's like, hey, tanks, why don't you soften up and feel the pain of being a soldier? You've gotten too tough. Come down to the streets where the common man lives, and get to know his heart. I'm even weaker than the old guy who collects for NHK, and that's what I wanted to say to them.

Actually, "soft-Masutatsus" would have been just as good as "soft-tanks", but they wouldn't have been very cute so I made them tanks instead. If looking at those little soft-tanks doodling around makes you feel good about yourself, you're probably a weakling. Congratulations.