How many bike accidents are there in Japan?

I�fm looking to compare the rate of serious accidents while riding a bike in Japan to New Zealand. I searched for awhile but wasn�ft able to find any sources giving me a reliable figure. Does anyone know a reliable source on this? Thank you I�fm advance.

This is the top result that I get from a quick Google search:
https://www.sonpo.or.jp/about/useful/jitensya/stats.html

Looks reliable to me.

Maybe also these people at the cycling embassy can help you:
http://cycling-embassy.jp/

That would be an inquiry to the Justice Ministry or a search on the police websites. I know when I did my last drivers license renewal one of the more interesting items in the book I was given were the accidents/deaths for cars, motorbikes, cyclists and pedestrians. Following a quick line of searching I think the site you need is:
https://www.npa.go.jp/publications/statistics/koutsuu/toukeihyo_e.html
Then you can get to monthly reports like:
https://www.e-stat.go.jp/en/stat-search/files?page=1&layout=datalist&t...

Given the lack of bike helmets, lights at night, riding on footpaths, not looking and general poor skills I am surprised the accident/death rates are not higher for cyclists.
I also notice motorcyclists don't bother wearing helmets properly and the lazy attitude to seatbelts drives me nuts, not like the NZ experience. On a single check of the dataset, half of fatalities were not wearing a seatbelt.

Whatever the exact figure is, I guarantee you that it's significantly less than the NZ and other Western rates.