A company that has been building a number of skyscrapers around Tokyo's Shibuya Station over the past several years has completed a huge underground facility, tasked with safeguarding the major transit hub against flooding in times of torrential rain.

The water storage facility, built by Tokyu Corp. in a 10-year project, can hold some 4,000 tons of rainwater, or enough to fill nine 25-meter swimming pools, according to the major railway and real estate business group.

The facility, located about 25 meters beneath the station's East Exit plaza, is usually empty. But when a downpour hits the area, it is designed to collect rainwater through storm drains. Once the weather gets better, the water will be discharged into the sewer via pumps.

Photo taken on Aug. 19, 2020, shows an underground facility built by Tokyu Corp. in Tokyo's Shibuya area to store up to about 4,000 tons of rainwater. The huge cave-like facility about 25 meters below JR Shibuya Station, unveiled to the media the same day, is meant to prevent the railway station's platform from flooding in the event of torrential rain. (Kyodo)

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Shibuya, home to youth culture and one of Tokyo's most bustling neighborhoods, has been undergoing large-scale redevelopment. Among buildings recently constructed around the station include the 47-story east tower of the Shibuya Scramble Square commercial and office complex.

With its famous Shibuya Crossing, the area has also been a popular destination for foreign tourists.

The name Shibuya includes the Japanese word for valley, and the area has a valley-like terrain along Shibuya River. The station, positioned at the bottom of the valley, has been hit by flooding several times in the past when central Tokyo has experienced a deluge of rain.

Tokyu invited journalists to visit the rainwater storage facility on Wednesday. Despite the cooler temperature inside, the humidity was extremely high.

"We decided to take 10 years to build this," said a Tokyu official. Because there is a mega bus terminal on the ground, "the construction had to be done at night, and little by little."

The Tokyo metropolitan government will be in charge of the facility's operation from the end of this month.