Green is the colour of balance and responsibility in spiritual and mental terms. Green is also the halfway mark to Black belt.
It’s called the grade of responsibility because it is an official sempai grade. Sempai starts here. The lift to higher knowledge in all avenues of karate. At this point you have stabilised and buried all your fundamental basics in the store place of your mind called the subconscious mind.
Now it’s the development of intermediate knowledge that requires you do two and three – or even four and five – things at once. It requires deep focus and smart thinking.
Balance your knowledge by bringing balance to your mind. Be responsible for what goes into your mind. Green belt is the mindfulness grade. Be eager to learn. Grasp knowledge like a dry sponge on a wet table.