Looking at published medical literature, it was easy to find at least 4 major hospitals in Japan routinely using ivermectin to treat COVID-19 (not in a clinical trial).

Fukushima Medical University, University of Occupational and Environmental Health, Yokohama Municipal Citizen's Hospital and Osaka Habikino Medical Center all use ivermectin. This makes it clear that ivermectin is commonly used in Japanese hospitals to treat COVID-19.

https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7925270/ https://pubmed.ncbi.nlm.nih.gov/33867266/ https://europepmc.org/article/PMC/PMC8612813 https://europepmc.org/article/MED/34023221

Unlike Japan, most people in the US have to go to court to get ivermectin.

From 20,000 coronavirus cases a day to under 500: How did Japan do it? https://www.latimes.com/world-nation/story/2021-10-18/japan-puzzled-coronavirus-control-success

The LA times is "puzzled" by how Japan did it. The answer is clear as day. They did it the same way as Uttar Pradesh and numerous other Indian states - by using ivermectin.