The only instance of tradition on that page says it is contained within plays and literature. This is different than saying that the actual act itself, in real life, was a tradition.

The reasonable thing to do is look up the ja.wiki

Here's one citation (14-15 double suicides a year Taisho era in some fashionable district)

https://hdl.handle.net/20.500.14094/0100275627

I agree that suicide ideation is not exactly prosocial, but I think being tolerant of misinformation is a worse look on HN?