The 29-year-old Krishan sustained a cut below his left eye in the high-voltage clash, which, according to team sources, he competed with a shoulder niggle.
He was the only Indian boxer in action on the day.
Okazawa dominated from start to finish, who seemed like a nimble-footed dancer in the ring, controlling the proceedings with utmost ease against the two-time Olympian Indian.
The 25-year-old Okazawa is of Ghanaian decent and was a silver-medallist at the 2019 Asian championships and a quarterfinalist at the world championships the same year.
He will next face Cuba's third-seeded Roniel Iglesias in the round of 16. Iglesias is the 2012 Olympic gold-medallist and also a former world champion.
On Sunday, six-time world champion M C Mary Kom (51kg) and Commonwealth Games silver-medallist Manish Kaushik will compete in their opening bouts.