And it’s not just Japanese companies that manage to pull that off. Some others have managed to do the same. See: Lego, for example. They branched out into movies, games, and parks, but their primary and core product remains bricks.
Lego's original core competency was toys, but not plastic ones. The original Lego toys were nearly all wooden, but they gained success with the plastic bricks.
It's unfortunate how many spinoffs they've had that failed.
[1] https://business.time.com/2012/07/23/innovation-almost-bankr...