So I'm about to move to Tokyo and become a bike commuter...what do you guys wear when commuting in heavy rain?

one just like this one. but single color. and bags on my shoes bc I am too poor for proper shoe waterproofing.

Equip your aluminum framed bike with rack and fenders. Wear a pair of shorts, a pair of flipflops, and a hooded Poncho on rainy commutes.

Carry a change of clothes in your panniers. Change, once you arrive at your destination.

PS.

Make certain that you have disc brakes on your inclines!

I would just take swimming lessons before moving.. and then ride your bike in a wetsuit with flippers just in case you have to bail out and swim.

I'm on my second winter , with my Rain Cape in the Rt fwd pannier to put on when the sky opes Up.

Post Fukushima Japan, I suggest a Geiger counter too..