Yahoo Japan is refusing to stop the sale of ivory on its website
Even Marissa Mayer, CEO of Yahoo, has tried to stop the trade - but the business argues that so long as no laws are broken, people should be able to trade whatever it wants on the site.
Yahoo Japan (which Yahoo owns a minority stake in) operates Japan's largest online auction site.
And it is happy to let ivory be sold on it, as long as that ivory is - supposedly - imported into Japan before 1989, when a ban on international shipments was introduced.
Meanwhile, there has been a sharp rise in poaching on the African Savannah - and some wildlife groups fear that sales on sites like Yahoo Japan are contributing to this.
"We want to provide an internet auction site where people can trade freely, and at this moment we have no intention of banning legal trading without any reason," a spokesman for Yahoo Japan said. "We don't believe the ivory sales contribute to a fall in elephant numbers."
The population of African elephants - the main source of African elephants - has dropped 30% between 2007 and 2014, to less than 380,000. (They're on the World Wildlife Fund's (WWF) vulnerable list.)
Meanwhile, sales of ivory on Yahoo Japan have risen exponentially. 28,000 ivory pieces were traded on the platform in 2015 - more than seven times as much as a decade early, including 438 whole tusks, according to a recent report by the Environmental Investigation Agency (EIA).
Ivory is traditionally used in Japan for carved "hanko" name seals. But because much of Japan's ivory is unregistered, wildlife groups say Japan provides an opportunity for unscrupulous traders to register poached ivory for sale to Chinese traders.
Marissa Mayer isn't happy about it
"Marissa has met up dozens of times with Yahoo Japan on this issue," said a source with knowledge of the meetings. "Sometimes it's engagement with board members and sometimes it's meetings with the CEOs," he added.
The Yahoo Japan spokesman confirmed that Mayer has met its CEO Manabu Miyasaka, but declined to give details of the talks.
Ron Bell, a counsel for Yahoo, issued a statement last year describing the relationship with Yahoo Japan as one of "passive ownership."
Aside from having its brand above the door, Yahoo has a 35.6 percent stake in Yahoo Japan, second only to the 36.4 percent owned by the Softbank Group controlled by billionaire businessman Masayoshi Son. (In Japan shareholders that own more than a third of a company's stock has the right to veto board decisions.)
The U.S. company declined to comment further when asked whether it would consider taking action.
Yahoo Japan declined to say how much it earned in commissions from online ivory sales. But EIA estimated it was $7 million in 2015 - making just a tiny part of the $5.52 billion revenues Yahoo Japan reported for the 2015/16 financial year.
It's only legal to sell historic ivory in Japan - but activists fear the law is being circumvented
At CITES meeting in September, 182 countries approved a non-binding proposal to end domestic trading that animal rights groups say has spurred a revival in poaching.
Japanese officials, however, have so far said they are reluctant to stop trading on Yahoo Japan or elsewhere because they believe only pre-ban ivory is traded.
"If you closed down a well-established market like Japan it would not stop the killing. It would drive the market underground," said a spokesman from the Japan's Ministry of the Environment.
Nobody, however, knows how much ivory came to Japan before 1989 or how much remains unregistered, raising suspicions about shipments to China.
"Regrettably, that makes us vulnerable to criticism," said the official from the environment ministry, which estimates there is about 2,000 tons of ivory in Japan, of which only 300 tons is registered.
That registration and accompanying third party confirmation is subject to few checks to stop poached ivory entering the market, animal rights groups say.
"The third party requirement is the problem, even family members are allowed," said Masayuki Sakamoto, an official at EIA. "It is kind of official laundering."
Meanwhile, China said two weeks ago it will ban the domestic trade by the end of 2017, shutting the door to the world's biggest market for poached ivory.