The important thing is that the distinction between bikes and motorcycles are a little different in Japan than elsewhere.

Elsewhere, there's a speed or weight limit, where if the e-bike can travel at greater than that speed without pedaling, it's classed as a motorbike, otherwise it's a electrically assisted bicycle and follows bicycle rules.

In Japan, the distinction is if the bike can move at all on its own without human input (i.e. it has a throttle), then it is a moped and classed the same as a motorbike, requiring a licence (a <50cc motorbike or general automobile licence), registration plate, liability insurance, helmet, and a prohibition against drunk and distracted driving (note: now manual bicycles are subject to the same prohibitions as well). The law was clarified this year that for a moped-class e-bike, even if the motor is switched off, is still the same, it doesn't drop to a bicycle class.