From 1 April 2020 Tokyo banned smoking in indoor public places. The ban had been scheduled for 2 years following legislation in 2018 as part of the preparations for the 2020 Olympic games. Many restaurants have built smoking rooms which are exempt from the legislation.

Source: https://uk.reuters.com/article/uk-health-coronavirus-japan-smoking/smoking-diners-to-take-it-outside-as-tokyo-ban-kicks-in-idUKKBN21I0X4