OK. I can’t really vouch for their age or whether they have actual ninja skills, but there are radioactive wild boar causing trouble near Fukushima, Japan.
As you probably remember, The disaster at Fukushima-Daichi Nuclear Plant, in March of 2011, which was triggered by a tsunami and resulted in the meltdown of three nuclear reactors, has led to a bit of a mess. According to experts in the region, radioactive wild boar have been “breeding like rabbits” and their population has swollen to over 13,000 in just the last few years that they’ve been running around the exclusion zone. That’s a 330% increase over the population tally before the meltdown… and it’s wreaking devastation upon the crops. As they encroach on populated areas, they’ve also been responsible for injuring several residents who encounter them walking through the streets of small towns.
The best solution that they can come up with right now is to offer a reward for their deaths. Hunters are invited to head out and collect a bounty on the mildly mutated piggies. to date, this has had little effect on the population, which appears to have moved into abandoned houses to raise their young (THEY THINK THEY’RE PEOPLE!!!).