That buff was designed to hit the continental United Stated with Biological weapons, using with unlimited range, and an operational ceiling of about 38,000 feet.
Most likely it would have been poorly armored, and not as capable as the B-29, despite its clear advantage in range to target, had they come into service. I'm glad it's not in AH, nor should it be. If it does get in, perk the ba-jeezees out of it

As for Japans Biological weapons program, they were the frontrunners in that area. Josef Mengle gets all the notoriety, but Japan was clearly the frontrunners in this area during that time.