The Japanese government (Prime Minister Shinzo Abe) announced in December 2017 that the 125th Emperor Akihito would abdicate on 30 April 2019, and that the 126th Emperor Naruhito's reign would begin as of 1 May 2019. On 19 March 2020, the Emperor Emeritus Akihito and his wife the Empress Emerita Michiko moved out of the Imperial Palace, marking their first public appearance since the abdication. In extension of his father's interest in marine biology, who published taxonomic works on the Hydrozoa, the Emperor Emeritus is a published ichthyological researcher, and has specialized in studies within the taxonomy of the family Gobiidae. He has written papers for scholarly journals such as "Gene, Ichthyological Research," and the "Japanese Journal of Ichthyology". He has also written papers about the history of science during the Edo and Meiji eras, which were published in "Science" and "Nature". In 2005, a newly described goby was named "Exyrias akihito" in his honour, and in 2007 a genus "Akihito" of gobies native to Vanuatu also received his name. The following table includes the official visits made by Emperor Akihito, along with Empress Michiko, following succession to the throne on 7 January 1989. The list includes all the visits made up to 31 December 2017. Although Empress Michiko has made two official visits on her own, in 2002 (to Switzerland) and 2014 (to Belgium), they did not include the Emperor and are not included in this table. The Emperor emeritus Akihito and the Empress emerita have three children, two sons and a daughter as their parents. Akihito's patriline is the line from which he is descended father to son. Patrilineal descent is the principle behind membership in royal houses, as it can be traced back through the generations, which means that Akihito is a member of the Imperial House of Japan.