ihasana

Are you Japanese or did you travel there for the experience? If you have a chance, I would suggest travelling as much as possible to learn about the different cultures and the world in general (I know bad timing with Covid but I think it's justified in your situation if you have been vaccinated). Travelling the world opens your mind and senses in a lasting way.

This is more a question for a medical doctor. I don't know the answer to the question but the pathogenesis of rheumatoid arthritis and osteoarthritis are quite different.