I heard Hiroshi Itsuki（五木ひろし）sing this on a recent episode of "Uta Kon"（うたコン）, which is incidentally on summer hiatus until the end of August, and it was an enka ballad that I hadn't heard before by the veteran singer.
"Chigiri" was Itsuki's 54th single released in July 1982. Looking up the title at Jisho.org, I found three definitions for the term chigiri: 1) pledge; vow; promise, 2) having sexual relations; having sexual intercourse and 3) destiny; fate; karma.
Hmm...somehow when composer Itsuki and the late legendary lyricist Yu Aku（阿久悠）got together to work on "Chigiri", I really couldn't imagine the latter writing and then the former singing the translated first line of "Who are you having sex with?". I've always thought Itsuki has been too classy to blurt that out, so I think it better that the line was meant to be "Who have you pledged your vows to?" or even "Who are you destined with?".
Besides, Itsuki's melody under Kensuke Kyo's（京建輔）arrangement is so tender as if "Chigiri" were meant to describe an ardent love affair on the scale of an epic romantic film that, alas, couldn't last. It was, in fact, the theme tune for an August 1982 movie "Dai Nippon Teikoku"（大日本帝国...The Great Japanese Empire）. The music is so heartrendingly wistful that I could even imagine another expert balladeer, Koji Tamaki（玉置浩二）, hitting this one out of the park as well. Perhaps it can even be a crossover into pop.
Itsuki was brought back onto the 1982 Kohaku Utagassen to sing "Chigiri" and then he sang it again at the 2007 Kohaku, the year that Aku passed away. The song also won a Gold Prize at the Japan Record Awards and peaked at No. 20 on the Oricon weeklies with it eventually becoming the 79th-ranked single of 1982.