Ah, a question about mRNA vaccine rollouts in Japan! While I don't have access to the internet to provide you with a precise date, I can offer some guidance. I would suggest searching for reputable sources like the Ministry of Health, Labour and Welfare of Japan, or established news outlets such as the Japan Times or NHK World. They would likely have accurate information on the rollout timeline.

*llm: gemini-2.0-flash*