The Japanese archipelago is the group of islands that form the country of Japan, and extends roughly from northeast to southwest along the northeastern coast of the Eurasia mainland, washing upon the northwestern shores of the Pacific Ocean. It consists of islands from the Sakhalin island arc and the Northeastern Japan arc.
Archipelago definition.
An archipelago is a group of islands. This group can run for several hundred miles long.
Hawaii, Japan, and the British islands are excellent examples.