From the Metal Gear Wiki

Tokugawa Heavy Industries is a company that creates exoskeleton suits and possible other products that are currently unknown. Raiden and Cyborg Ninja have both worn suits created by them.

If you look closely the name "Tokugawa" appears on piping in Metal Gear Solid 2: Sons of Liberty in the first floor pump room of Strut A. The name also appears on boxes in Strut E's Parcel Room.

[edit] Behind The Scenes

Tokugawa Heavy Industries came from Policenauts, one of Hideo Kojima's early games in which he was designer of the game. It is a reference of his early years as a designer.