Kumamoto is pretty safe but not exactly crime free. If you’re curious about the place that got hit, it’s in the following Japanese article:
https://japantoday.com/category/crime/Watches-worth-¥43-million-stolen-from-Kumamoto-store
The name of the store is “Second” (and it’s a couple blocks behind Tsuruya).
https://japantoday.com/category/crime/Watches-worth-¥43-million-stolen-from-Kumamoto-store