Goldman Sachs Group Inc. is buying a stake in TBM Co., a startup that has become known for its technology that turns limestone into paper.

The two parties confirmed the deal on Thursday. TBM, which makes business cards, posters, catalogs and stickers from limestone, is seeking to raise a total of ¥3.1 billion ($27 million).

Goldman Sachs is seeking to make investments in 10 to 15 Japanese startups through 2019, people with knowledge of the matter said. The investment is part of a renewed push by Goldman Sachs to seek out and back potential Japanese unicorns that can compete globally with their technology while being environmentally responsible, said the people, who asked not to be identified because the information is not yet public.

TBM's Limex paper is made without water. By comparison, it takes 100 tons of water to make a ton of regular paper. That also required 20 trees, while the TBM process uses less than a ton of limestone together with 200 kilograms of polyolefin.

Representatives from Goldman Sachs visited TBM more than three years ago as a potential investment target because their technology is unique and the firm can be bigger than a unicorn, they said.

Nobuyoshi Yamasaki, TBM's chief executive officer, said in an interview last year that he's aiming for an initial public offering by 2020. The company was founded in 2011.

Prior to the global financial crisis in 2008, Goldman Sachs had poured ¥550 billion into Japanese companies, including a lender, an electronics company and an amusement-park operator. It then scaled back investments in the decade that followed.