Originally Posted by Toudiyama[NL]

Osu or oss, is considered rude in Japan, other then some Karatestyles noboby uses it, kyokushin being the style that is really know for it, if the greet/bow or if they understand something or to acknowledge
Other styles do not use it in any circumstances because of it's rudeness


Ki-Ai as far as I know doesn't mean Fighting Energy but harmonious Energy, in that sense it is the same as Ai-ki