Are the Chuo, Keiyo and Yamonte lines covered by the suica? You can use it on virtually every commuter train network in the area and most other areas of Japan. So YES you can use it on those trains. Here is the map for local JR Lines in Tokyo area.

Yes, in 2026, the Suica card (as well as PASMO and other major IC cards) works perfectly on the JR Keiyo Line. This is particularly important for tourists because the Keiyo Line is the primary train route connecting central Tokyo (starting at Tokyo Station) to Maihama Station, which is the gateway to Tokyo Disneyland and DisneySea. Since the Keiyo Line is operated by JR East, the same company that issues the Suica card, it is the native payment method for this route. You simply tap your card (or your iPhone/Apple Watch with a digital Suica) at the ticket gates at both your departure and arrival stations. The correct fare is automatically deducted based on the distance traveled. This saves you the hassle of using paper ticket vending machines, which can be confusing at the busy Tokyo Station hub. Just ensure your balance is at least the minimum fare before entering the gates. If you are using the "Welcome Suica" (the version for short-term tourists), it also works seamlessly on this line and all other JR lines within the Tokyo metropolitan area.