Why Olive Wagyu is so expensive

Olive wagyu has been called the rarest steak in the world. At over $500 a pound, it's one of the most expensive meats you can buy. In Shōdoshima, Japan, Masaki Ishii creates olive wagyu by feeding his cattle the waste from local olive groves. An olive-wagyu cow is worth 1.2 million yen, or over $9,000. So, what makes olive wagyu different from other varieties of wagyu? And what makes it so much more expensive?