Sargasso sea
The Times called the sea between Korea and Japan the 'Sea of Japan' instead of the 'East Sea'.
Japan sea.
Sea of Japan
The Asian Countries that occupy the Choson Peninsula (Hanguk Peninsula in South Korea, Korean Peninsula in English) are North Korea (the Democratic People's Republic of Korea) and South Korea (the Republic of Korea). This peninsula extends from Asia between the Sea of Japan & the Yellow Sea.
Japan is to the east. Russia is to the north and west, North Korea and South Korea to the west. China no longer has any seacoast on the Sea of Japan.
That's "East Sea" a.k.a. "Sea of Japan".
The Sea of Japan lies between Japan and the mainland of Asia
The Sea of Japan is between Japan and North Korea.
A sea passage between Korea and Japan
Yes, this is true. On South Korea's west is the Yellow Sea and on South Korea's east is the Sea of Japan. However, given the antagonism between South Korea and Japan, Koreans call the Sea of Japan as the East Sea, so there may be some confusion on the names.
The islands of Japan are situated between the Sea of Japan and the Pacific Ocean. The Sea of Japan separates Japan from South Korea, North Korea, and Russia.