What modern prefecture does the ancient Japanese place name 'Wanokuni' correspond to?

He is facing many difficulties due to gender identity disorder.

This company demands uniformity in all projects.

This design has uniformity in color.

This vitamin is water-soluble, so it easily dissolves in water.

This cold is highly contagious, so please be careful with prevention.

Database transactions need to ensure their atomicity.

Flexibility is necessary for success.

This math problem is based on the principle of additivity.

This problem can be solved using the principle of linearity.