TMK has expanded the facilities of the Yokohama branch. This is because the service is increasing with the manufacture of parts in Niigata unit.

The Yokohama branch has almost the double of the space on the first floor, about 1,030 square meters. The parts are manufactured in Yokohama and then they are sent to Niigata, where TMK completes the assembly of the trains for the Yamanote line in Tokyo.