Authorities and companies in the country have been offering "smiling lessons" as they get used to taking their masks off in public after the government downgraded the threat posed by coronavirus.
The classes have been on offer since last year in anticipation of the guidelines being relaxed and business is booming since risks associated with the disease were lowered earlier this week.
Miho Kitano, owner of the Smile Expression Muscle Association, told The Daily Telegraph newspaper: "We are extremely busy now because people want to be seen smiling again.
"Japanese people have been wearing masks for more than three years now and some say they have almost forgotten how to smile."
Kitano started her company five years ago but inquiries have soared since it was announced that Covid restrictions would be lifted.
She said: "Smiling is very natural and very important because it's a signal to the people that we meet that we accept them.
"A smile has to be natural to get through to the other person, but for anyone who does not smile much, the brain forgets how to use the facial muscles."