Only the Ring Finger Knows is m/m romance. It was originally published in Japanese in 2001.
My review includes a few spoilers. Also, I'm still on my extended "not going to include read-alikes" break. I will say this, though, the relationship dynamics reminded me a lot of His Favorite. I wonder if that series was inspired by this one?
Review:
Yuichi seems like the most perfect guy at Wataru's high school. He gets good grades, has good looks, is good at basketball, and gets along well with everyone. However, a chance encounter at a water fountain shows Wataru another side of Yuichi, one that's cold and sarcastic. Wataru can't remember ever even talking to Yuichi, so why does the guy hate him so much?
The situation only becomes more awkward and upsetting when Wataru and Yuichi discover they've accidentally swapped rings. At their school, wearing matching rings and/or wearing a ring on your ring finger signifies that you're dating someone and, shockingly, Wataru and Yuichi's rings not only look exactly alike, but they also fit on each other's ring fingers. The matching rings are, of course, an indication that there is romance in Wataru and Yuichi's future.
