The Kodansha Ltd. publishing house said it has lodged a protest with Inc.'s Japan unit, saying the online retailer unilaterally withdrew all of more than 1,000 titles from its subscription-based e-book service.

Another publisher, Kobunsha Co., likewise said Monday that its 550 titles have been pulled from the service, called Kindle Unlimited, that was launched by Amazon Japan on Aug. 3.

The service offers subscribers unlimited access to 1.2 million foreign books and around 120,000 Japanese publications, including manga and magazines, for ¥980 a month.

According to a source in the publishing industry, popular manga and photo collections started disappearing from the Kindle lineup in mid-August. Amazon told publishers that some titles saw more-than-expected demand and its budget had run out, the source said.

In an attempt to expand its lineup, Amazon had told the publishers that it would offer them extra payments in addition to regular fees until the end of the year, according to the source.

In the days after the service started, Kodansha noticed that nearly 20 titles were pulled and asked Amazon to reinstate them. It found out that all of the more than 1,000 titles were gone in late September.

Amazon Japan said it cannot comment on specific business deals.