The official name of the Rainbow Bridge is Shuto Expressway No. 11 Daiba Route - Port of Tokyo Connector Bridge - that’s no fun. :p
The name Rainbow Bridge was decided by the public, and while the bridge is actually white, some steps were done to create an appearance to justify the name - some poles on the bridge’s sidewalk are actually painted in rainbow colors and, at night, there are 3 kind of lights, red, white and green.
However, viewed from the side, the bridge looks green:

Rainbow Bridge, Tokyo

EXIF Info:

Yesterday’s Japan Photo: Mount Takao Tengu