The main shock of this one at 7.0 killed 277 people so sadly I think it’s pretty likely there will be some deaths.
Japan is _very good_ at tearing down old buildings and building better in their place; but it doesn't mean that there are zero old buildings around.
Earthquakes aren't a perfectly repeatable occurrences you can run a regression test against.
Then there was the developer who tore down a couple of houses over a weekend before the historical commission had a chance to meet and formally confer historic status on the rotting, worn out properties.
Sadly there has been a bunch of pretty devastating earthquakes in recent years. In particular in Kumamoto the one in 2016 (magnitude 6.5) was huge and many of the houses built at lower standard or not in great shape anymore got partially or totally wrecked. Right now the house that are left are relatively well built.
The bad news is, that still doesn't help as the cumulative damage can still bring them down, and they're still subject to landslides, water damage, and other second order disastrous events.
https://en.wikipedia.org/wiki/1999_%C4%B0zmit_earthquake
It took around 10 years until the city felt "normal" again (source: a close friend lives there).
My point is, it's never easy to rebuild.