> VAERS reports?
... Aren't proof. VAERS is data collection, not analysis. It's a giant anecdote database. There is no vetting on the input data, which is self-reported.
There is a VAERS entry describing someone being turned into the Incredible Hulk after taking MMR vaccine.
https://www.medalerts.org/vaersdb/findfield.php?IDNUMBER=221...
Fortunately, there are tests and analytics on the side-effects of Ivermectin that don't rely on VAERS. You can find most of them listed in the FDA front-matter for the drug, because it was approved for other uses besides COVID. The approval process includes grasping side-effects.
The US decided, ages ago, that "snake-oil" (unproven drugs with side-effects) were something the government would step in and stop because people suffering and dying are desperate and easily-cheated. Other nations have different histories.
(... Regarding Japan, I'd double check primary sources. https://www.newswise.com/articles/misleading-reuters-article...)