I’ve heard this too. They have a term for dying due to being overworked called Karoshi. People who specifically commit suicide due to overwork are called Karojisatsu.

This site has some stats on suicide due to overwork, but it doesn’t have a comparison to suicide due to other reasons. It’s definitely a thing though!

https://www.statista.com/statistics/622325/japan-work-relate...

No data sorry, just a belief from Japan documentaries stating that people work a lot more than the usual 8h a day and quite a strange culture to not leave the office until your boss does, which is usually really late (can't really say an estimate, I've seen 8pm but also 10pm sometimes).