Indonesia is 5 times larger than Japan.
Area: 1,904,569 km2 World Factbook
Population: 253,609,643 (July 2014) World Factbook
Indonesia, officially the Republic of Indonesia, is a sovereign state in Southeast Asia and Oceania. Indonesia is an archipelago comprising 13,466 islands. Wikipedia
Area: 377,915 km2 World Factbook
Population: 127,103,388 (July 2014) World Factbook
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. Wikipedia