The new owners of Evermay: Ryuji Ueno and wife Sachiko Kuno, left, at a party last year with Japanese Ambassador Ichiro Fujisaki and his wife Yoriko Fujisaki. (Kyle Samperton/Washington Life)

Never heard of them? The founders of Bethesda-based Sucampo Pharmaceuticals keep a very low profile and are little known outside the medical or Japanese-American communities.

“This was a personal transaction,” a spokesman for the company told us Monday, saying the couple had no comment on the sale.

The husband and wife scientists founded Sucampo in 1996 and hit it big by developing drugs derived from fatty acids. In 2006, the FDA approved Amitiza as a treatment for chronic constipation; a year later, the company went public and never looked back.

Evermay Estate. (Stu Estler)

Ten years ago, they created the S&R Foundation to support medical researchers and performing artists here and in Japan. Kuno, 56, is a fan of the Washington National Opera; Ueno, 57, collects cars — he boasts a membership in the Ferrari Club of America — and races them as well.

And they like buying houses. . . a lot. According to public records, the couple owns three mansions in a quiet Potomac neighborhood bordering the C&O Canal National Historic Park (and just sold a fourth on the same block for $3 million). They also have a Georgetown rowhouse, two waterfront homes on Maryland’s Eastern Shore, and a Manhattan condo.

And now Evermay. Originally listed at $49 million in 2008, it was the most expensive price for a house in Georgetown (and seemingly the perfect residence for Oprah, when everyone was convinced she was buying a house in D.C.). The property, which dates back to 1801, sits on more than three acres of prime real estate and is listed on the National Register of Historic Places.

Speculation about the new owners heated up after the deal was finalized in May. Ueno and Kuno managed to keep their identity a secret until the Wall Street Journal reported the news Friday. The $22 million sale — less than half of asking price — comes just shy of the record: In 2007, developer Herb Miller sold the Bowie-Sevier house, another historic Georgetown mansion, to Robert Allbritton for $24 million.

Read earlier: No, Oprah’s not buying Evermay, 1/5/09

Evermay: $49 million. In this economy?, 10/4/08