Ask Professor Goldsbury, but "Domo Arigato" is "Thank you very much."
Someone told me long ago that "Osu" is Japanese for "Hell Yeah!"
Yes, it looks like I will need some translation.
The one bit of Japanese they have on my testing requirements says:
Koszonom (accent marks missing, but means thank you in Hungarian) is equivalent to arigato gozaj masz.
Definitely not something they will be able to explain, so I think your right - time to ask someone who knows japanese better. (Like Professor Goldsbury)