Japan is a country in East Asia, sharing maritime borders with Taiwan, China, the Korean Peninsula and Russia. It is a first world country, with the third highest economy in during the 2010s. It's military, the Japanese Self-Defense force, although for "self-defense" only, is one of the most sophisticated forces in the world. Territorial disputes with China and Russia, as well as threats from North Korea, have rendered the JSDF prepared for invasion and war.
In an event of a zombie apocalypse, Japan would be hit hard due to it's economic and trade connections around the world. Furthermore, the country has a strict firearms policy, and it's police forces are the one of the least armed in the world. However, Japan makes up for it in terms of the JSDF having advanced weaponry and being experiences with natural disasters such as earthquakes and tsunamis. Lastly, U.S. forces stationed in Japan would most likely reinforce the JSDF should a zombie outbreak occur in the Home Islands.
Japan is a setting in handful zombie works of fiction, namely the Resident Evil film series, The Zombie Survival Guide: Complete Protection From the Living Dead, World War Z, and the manga High School of the Dead and Apocalypse No Torride.