The Kemmu Restoration was a period of Japanese history that occurred from 1333 to 1336 AD. It marks the three year period betweem the fall of the Kamakura shogunate and the rise of the Ashikaga shogunate, when the Emperor had re-established Imperial control.
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... devices come with electronic rev counters and light emitting diodes powered by a little generator embedded in the gyroscope.
The physics of this device looks confusing ...