A member of Japan Ground Self-Defense Force shows the mattress which Yamato Tanooka used inside a building at JGSDF's Komagatake exercise area in Shikabe town June 3, 2016 Kyodo/via REUTERS

A member of Japan Ground Self-Defense Force shows the mattress which Yamato Tanooka used inside a building at JGSDF’s Komagatake exercise area in Shikabe town June 3, 2016 Kyodo/via REUTERS

A member of Japan Ground Self-Defense Force shows the mattress which Yamato Tanooka used inside a building at JGSDF's Komagatake exercise area in Shikabe town June 3, 2016 Kyodo/via REUTERS

June 3, 2016 12:09 AM (UTC+8)