"Let's swamp the walls of Shibuya."

That's railway Tokyu Corp.'s latest catch phrase for a campaign to cover the walls of stores and housing in Tokyo's bustling Shibuya district with advertisements.

The company is aiming to use up to 100 locations for the campaign by April 2019, not only to turn them into a new ad medium but also to improve the dim and scary image of Shibuya's graffiti-flooded back streets.

Ads on street-side walls aren't popular yet in Japan. Tokyu, therefore, will look for walls in conspicuous places and maintain them on behalf of the owners. If the owners agree to the plan, Tokyu will erase any graffiti and pay them in accordance with ad size and period of time.

Ads in Shibuya tend to be large and placed higher up on buildings. But the ads on street walls will be placed at eye level, which Tokyu believes will provide a great visual impact.

The company has been working on 30 places involved in the project since July. And in September, Tokyu will hold a street art exhibition in collaboration with young street artists. It is also considering extending the campaign to walls beyond the streets of Shibuya.

"We hope that different forms of expression in different places will also make people enjoy the process of searching and finding them," said a Tokyu official.