Kento Momota tested positive for coronavirus on Sunday, prompting the withdrawal of all Japan's players from this month's Thailand Open.
Kento Momota is one of Japan's brightest hopes for a gold medal on home soil at the coronavirus-postponed Tokyo Games next year.
Kento Momota beat Koshiro Moriguchi 21-12, 21-14 in the first round of the All-Japan championships.
Kento Momota on Wednesday announced his long-awaited return to competition, nearly a year after suffering serious injuries in a car crash.
Kento Momota's coaching offer -- for just two lucky students -- attracted a flood of applicants, ranging from parents applying for their children to fellow sports stars.
The accident, which happened hours after Kento Momota won the Malaysia Masters, killed the driver of the vehicle taking him to Kuala Lumpur airport.
Kento Momota could be out for two months after being injured in a car crash that killed his driver just hours after he won the Malaysia Masters.
Badminton world number one Kento Momota was injured and his driver was killed in a crash near Kuala Lumpur on Monday.
Kento Momota has played 73 matches this year, losing just six times, and admits that he has surprised even himself with his blistering form.