Emperor Kōkaku
By 1979, Emperor Shōwa was the only monarch in the world with the monarchical title "emperor." Emperor Shōwa was the longest-reigning historical monarch in Japanese's history and the world's longest reigning monarch until surpassed by King Bhumibol Adulyadej of Thailand in July 2008. On April 30, 2019, Emperor Emeritus Akihito abdicated from his reign due to health issues. The previous time abdication occurred was Emperor Kōkaku in 1817. Naruhito ascended on May 1, 2019, referred to as "Kinjō Tennō."