Someone mentioned about 'Sea of Japan', so I searched the word because I did not know where Sea of Japan was. When I saw the map "Sea of Japan" in your site, I was very surprised because the part you marked was called "East Sea", not Sea of Japan. All the people from Korea, and China learn as East Sea (marked as Sea of Japan in Wikipedia) and it is known as Korean territory. There is no such sea officially called, Sea of Japan in the world.
You should have marked as 'East Sea' not 'Sea of Japan'. If you think that part is Sea of Japan, please reply me with your proof.