Japan has relied pretty extensively on contact tracing, especially in the early days of the epidemic. The Japanese government was also paralyzed by the thought of losing the Olympics, and did everything it could to put up a smokescreen regarding its slowness to begin a vaccination campaign. They didn't have the vaccines, and didn't have a plan to distribute them, and pretended that the problem was "vaccine hesitancy." But lo and behold, the moment vaccines became available the demand was overwhelming, and Japan quickly went from being a worldwide laggard in vaccine deployment to being a high percentage country.