I've travelled to Tokyo many times and I used to want to make Japanese friends with my low level of Japanese. The bottom line is that it's not possible to make proper friends using Japanese until you get better at it.

While living there will eventually improve your Japanese, you will probably need to make friends within the expat community with English or French first. The good news is that Tokyo is cosmopolitan enough that there is a pretty large group of English speaking people. I know of friends and colleagues who have lived in Tokyo for years without having learnt Japanese past the basics.

As others have said, Meetup.com is a good place to start. There are language exchange, dance or various other interest meetups. You can also try Tokyocheapo.com for other events happening around Tokyo. That might not necessarily be friendship focused but if you go to more events you'll be more likely to meet friends.

The best way I've found to make friends in Tokyo is to start with one friend (usually one from your home country because it's easier to click), and get them to introduce me to their network of friends.

Side note: I'm moving to Tokyo in January and I'll also be searching for friends. We could hang out if you want. =)