One of the largest container ships ever built in Japan has started operating, amid intensifying global competition to lower shipping costs.

Major shipbuilders in Japan, including Imabari Shipbuilding and Japan Marine United, have been constructing six container vessels that are among the largest in the world. They are about 400 meters long and more than 70 meters high, the equivalent of a 25-story building.

A ship that was built in the city of Saijo in Ehime Prefecture set sail in late July.

The vessel can carry up to 24,000 containers, which improves transportation efficiency. It is also fuel-efficient with features to reduce water and air resistance.

Tsujii Hiroki, an official of the ship's operator, Ocean Network Express, says larger vessels reduce shipping costs, making it possible to compete with foreign rivals.