The 42-year-old, who was roped in for India's men's singles players in 2019, has been training Sindhu following the departure of fellow Korean coach Kim Ji Hyun after the Basel World Championship two years ago.
Sindhu, who had lost to Spain's Carolina Marin in the 2016 Olympics final, has been clubbed in an easy Group J, also comprising Hong Kong's Cheung Ngan Yi.
"There was a ban on eating ice creams on you during the 2016 Olympics, has another ban been imposed for Tokyo," he asked to a grinning Sindhu, who would be aiming to better the silver she won five years ago.
Fifth seed Sindhu will kick off her campaign with a clash against Malaysia's Soniia Cheah and is likely to face Japan's Akane Yamaguchi in the quarterfinals, provided she wins her initial rounds
Sindhu, who had won the coveted World Championship gold medal here in 2019, couldn't match the speed and accuracy of Marin during her 12-21 5-21 defeat in the final
Jayaram, who currently has a world ranking of 60, beat the 12th ranked Gemke 21-18, 17-21, 21-13 to set up a match against Thai eighth seed Kunlavut Vitidsarn.
Olympic silver medallist Sindhu expectedly outclassed Malaysia's world no. 92 Kisona Selvaduray 21-10,21-12 in a lop-sided second-round contest that lasted just 35 minutes
