Walmart is taking on Amazon in e-books in partnership with Japanese-based Rakuten Kobo

Walmart on Wednesday launched a digital book shop in a collaboration with Japanese e-commerce powerhouse Rakuten's electronic book service Kobo.

The Walmart eBooks website boasting more than six million titles along with audiobooks competes head-on with a core offering of rival Amazon.

Subscriptions to the Walmart audiobook were $9.99 monthly, compared to $14.95 for a comparable Audible service at Amazon.

"The launch of Walmart eBooks by Rakuten Kobo marks a milestone for our strategic alliance," Rakuten executive vice president Makoto Arima said in a release.

The shop stemmed from a strategic alliance Walmart and Rakuten announced earlier this year, according to the companies.

Digital books are available on Kobo eReaders and on applications tailored for mobile devices powered by Apple or Android software.

"Working with Kobo enables us to quickly and efficiently launch a full eBook and audiobook catalog on alongside our assortment of physical books," said Walmart US e-commerce and entertainment general manager Mario Pacini.

The move marks the latest effort by Walmart, the former number one US retailer, to counter the rise of Amazon.