Koide became the world's oldest living man after the death of another Japanese man, Sakari Momoi who was over 5 weeks older, on 5 July 2015 and later in November that year one of the 25 oldest living people. In December 2015, Koide was hospitalized for chronic heart problems. He died at the hospital of pneumonia and heart failure at 0:17am on January 19, 2016, only less than 8 weeks before his 113th birthday. 