The Kyokushin spirit is one of perseverance and pushing beyond one's limits. "Osu" (or "Osu no Seishin") embodies the spirit of Kyokushin — patience, respect, and appreciation. It is used as a greeting, a response, and an expression of understanding.

The character of Kyokushin is built through hard training, humility, and dedication. Every practitioner walks the path of self-improvement, not just in the dojo, but in everyday life.