Although it’s not fun to think about, it’s always best to be prepared for all kinds of scenarios during your travels, including the possibility of getting sick or injured. I recommend having a look through the following websites to understand what you might need in case of an emergency, how you can navigate getting help and which hospitals or clinics have staff who speak your native language.
List of English-speaking hospitals and clinics in Tokyo: https://expatsguide.jp/health-safety/medical-care/hospitals-clinics-tokyo/
Overall guide regarding emergency numbers, travel insurance, and more: https://www.jnto.go.jp/emergency/eng/mi_guide.html
This website includes numerous other resources: https://japantoday.com/category/features/lifestyle/what-to-do-if-you-require-medical-assistance-while-visiting-japan