500 km/hour maglev trains of JR Tokai running in 2027 became a dream. Super fast train line between Tokyo and Osaka will go through many tunnels. But a small part of the line between Tokyo and Nogaya falls in Shizuoka Prefecture. This prefecture opposes tunnel construction for environmental reasons. Therefore has not yet approved the construction of the tunnels on their land. If approved today, 9.8km long tunnel will take at least 10 years to build. Therefore it 2034 is the earliest date for completion. It is not realistic though.

https://english.kyodonews.net/news/2024/03/bd9e1d3aec6a-urgent-japan-rail-operator-gives-up-plan-to-launch-maglev-train-in-2027.html