Task: Question Answering
Input (English): Context: Succession is now regulated by laws passed by the National Diet. The current law excludes women from the succession. A change to this law had been considered until Princess Kiko gave birth to a son. Until the birth of Prince Hisahito, son of Prince Akishino, on September 6, 2006, there was a potential succession problem, since Prince Akishino was the only male child to be born into the imperial family since 1965. Following the birth of Princess Aiko, there was public debate about amending the current Imperial Household Law to allow women to succeed to the throne. In January 2005, Prime Minister Junichiro Koizumi appointed a special panel composed of judges, university professors, and civil servants to study changes to the Imperial Household Law and to make recommendations to the government. The panel dealing with the succession issue recommended on October 25, 2005, amending the law to allow females of the male line of imperial descent to ascend the Japanese throne. On January 20, 2006, Prime Minister Junichiro Koizumi devoted part of his annual keynote speech to the controversy, pledging to submit a bill allowing women to ascend the throne to ensure that the succession continues in the future in a stable manner. Shortly after the announcement that Princess Kiko was pregnant with her third child, Koizumi suspended such plans. Her son, Prince Hisahito, is the third in line to the throne under the current law of succession. On January 3, 2007, Prime Minister Shinzo Abe announced that he would drop the proposal to alter the Imperial Household Law. 
 Question: Who is Prince Hisahito's mother?
Output (English): princess kiko