Japan has said it will not be sending a government delegation to the Beijing Winter Olympics. It didn't use the term "diplomatic boycott" like several Western countries, including the U.S., but that is the least of China's concerns.

With Beijing Olympics only a couple of weeks away, the more significant threat for the organizers is Omicron. It has forced the organizers to update the playbook for athletes and officials who will be part of the Games. (https://www.wsj.com/articles/as-beijing-olympics-approach-omicron-heightens-pressure-on-vaccines-11639839507). And now, closer to the games, the country has also reported its first case of Omicron.

Having administered over 2.2 billion doses of the Covid-19 vaccine, China has covered almost all of its population and should feel confident about the Olympics.

China is steadfast about its 'zero-covid' strategy, and had hoped it could hold back the variant. But that has not happened with seven cases reported so far. The government also had to put the city of Xi'an, in the northeastern Shaanxi province in lockdown after it reported cases recently. The officials were tight-lipped on whether the virus was identified as Omicron or not. (https://www.aljazeera.com/news/2021/12/23/china-puts-city-of-13-million-in-covid-lockdown-before-olympics)

To keep the virus away from the capital just before the Olympics, Beijing administration had called on its residents not to leave the city and spend the holidays within the city. (https://www.globaltimes.cn/page/202112/1243306.shtml)

While asserting that it will continue implementing its 'zero Covid' strategy, it may be flexible during the Olympics. For instance, the officials of the Beijing organizing committee have been quoted as saying that a "certain number" of Covid cases is possible during the Games as many foreign athletes would be visiting the city, but it is confident of that there will be no large-scale outbreaks. The organizers are employing the 'closed-loop' management system. But rather than imposing a 'zero-covid' policy in the Olympics village, they would resort to quarantining of asymptomatic cases and hospitalization of positive cases. (https://www.globaltimes.cn/page/202112/1243316.shtml)

Read more:

Can China keep out Omicron and still hold the 2022 Winter Olympics?:
https://www.vox.com/22850441/covid-omicron-china-lockdown-olympics-travel-ban

How Will China Respond to the Omicron Variant?:
https://foreignpolicy.com/2021/12/22/china-omicron-variant-restrictions-olympics/