The test run from Doncaster to Dunbar was the first of a series north of the Border in the run-up to the trains entering service late next year.
Their superior acceleration will cut Edinburgh-London journeys by 22 minutes to four hours from 2020.
Even greater journey time reductions are expected on other Virgin Trains East Coast routes between London and Aberdeen, Inverness and Glasgow.
The Azumas will replace 1970s vintage “High Speed Trains” on the two north of Scotland routes, and another fleet on the Edinburgh and Glasgow lines which are nearly 30 years old.
The test train - currently known only by its 800 101 number - is expected to visit Glasgow next, followed by Aberdeen and Inverness.
It has yet to be fitted with seats, with the interiors still being designed.
The 65-strong Hitachi-built fleet, designed in Japan and built near Durham, is named after the Japanese word for east.
Some are purely electric, for the Edinburgh and Glasgow routes, while others will switch to diesel power for the non-electrified routes north of Edinburgh.
Hitachi Rail Europe Karen Boswell managing director said: “Passengers and enthusiasts in Scotland will be seeing more of the Azuma trains in the coming months as part of our rigorous test programme.
“Our UK-built fleet harnesses world-famous Japanese bullet train technology, giving passengers on the east coast main line the very best in quality and reliability.”