At least, not anymore. Most European countries permit alcohol levels of 0.5‰. 500ml of beer amount to about 0.3‰ which happens to be the legal limit in Japan. Theoretically, you could get away with a can unless the coppers decide you appear to be driving drunk regardless of the legal alcohol limits. Considering the fines, it's not a risk I would like to take.
I see you have got some good replies on our sister site, too.
One problem for me is that on a hot summer day when I go cycling I like to have a few beers. If caught, 3 hour safety class and I believe a 6000 yen fine now. Fines for other infractions are up to 50000 yen now...