I am not sure where you have heard this "news". If there were a new shinkansen that traveled more than twice as fast, it would be going well over 300 mph (500 kph). Perhaps you heard something about the maglev under development. It won't be ready til about 2027. https://en.wikipedia.org/wiki/Chūō_Shinkansen
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Perhaps you heard something about the maglev under development. It won't be ready til about 2027.
https://en.wikipedia.org/wiki/Chūō_Shinkansen
There's also the new Shinkansen line that opened in March, it runs up north to Shin-Hakodate in Hokkaido, if you're thinking of that?
https://www.japan-rail-pass.com/japan-by-rail/travel-tips/hokkaido-shinkansen
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