Can you play a Japanese N64 Game on a European console?

I found this

The japanese and USA machines are basically the same NTSC machines, and you can play both games on both consoles after breaking the plastic tabs inside the machine.

But the european N64 is a different machine, it is PAL. You need a converter to play other games. And the japanese and americans need a converter to play european games on their consoles.

But when looking at converters for N64 it looks like most of them don't work for most games, and recomandation is to buy a used Japanese/US N64 since they can be found rather cheap.

Out of the box, no. The Nintendo 64 has a region lockout chip which prevents NTSC (Japanese and US) games from running on a PAL (European) machine.

However, through the use of third-party devices, most games should work. I personally own a N64 Passport Plus which I use to play Hey You, Pikachu! on my own N64. It basically works by using a second, local cartridge to authenticate with the lockout mechanism.

I don't have first hand experience of this, but according to that Wikipedia article, some games won't work even with this - presumably, they perform additional hardware detection, so they might be hard to do anything about. It may be possible to somehow bypass these through Action Replay codes; I don't know exactly how these games perform those checks.

You could also buy a Japanese N64 and bring that home. You'll need a power converter to make it run on 230V, and a TV which will accept the input, but you could run any Japanese game that way, and any US game if you remove the plastic tabs.

As an alternative, if you have a European Wii, at least some of the games might be available on the Virtual Console, saving you the trouble of messing with adapters.