The Ozora is the offical competitiion Kendama, made in Japan. It is the only offical brand allowed at Japanese Kendama Competitions.It is the offical size, weight and paint finish on the ball.
The paint that is used on a kendama makes a very big difference on how hard certain tricks are to do. So for this reason different brands of kendamas might be easier or harder to do certain tricks. In general the softer the paint finish the easier the tricks are.