Prime Minister Fumio Kishida has appointed his son as a senior political aide, sparking speculation the 31-year-old was being groomed as an eventual successor and prompting criticism of nepotism.

Shotaro, the oldest of Kishida’s three sons, was named executive secretary to the prime minister, government spokesman Hirokazu Matsuno said Tuesday, adding that the appointment was appropriate.

"Appointments are about putting the right person in the right role based on character and expertise, and I believe this is no different,” he said at the regular news briefing.