Let them say what they wanna say, only our ring fingers know the truth.
Yuichi Kazuki is wealthy, handsome, intelligent, and adored by everyone at his school for being courteous and kind to everyone... except for Wataru Fujii. To make matters worse, in a high school where it's the fashion for couples to wear matching rings, Kazuki turns out to own a ring identical to the one that Wataru wears, a fact Wataru discovers only when he and Kazuki switch rings by accident. From that moment, it seems like nothing goes right for Wataru, and he can't figure out why he of all people is the only one to see this unexpectedly rude and arrogant side of Kazuki.
Only the Ring Finger Knows (Sono Yubi Dake ga Shitte Iru) is a Boys' Love Light Novel series with five volumes and a manga adaptation of half the first volume, written by Satoru Kannagi and illustrated by Hotaru Odagiri. The light novels were published from 2002 to 2008.
The series is often considered a Gateway Series to the Boys' Love Genre thanks to the pretty art and its work-safe nature (nothing beyond kissing in the manga and the sex scenes in the novels are quite tame as they focus on the feelings of the characters rather than describing the acts). All novels and the manga are licensed in the U.S. and Germany.
Only the Ring Finger Knows contains examples of:
- All Love Is Unrequited: The legions of Yuichi Kazuki fangirls, especially Mai Tachibana and Karin's friend. Possibly Mizuho, Yuichi's ex (this case is very messy because before dating Yuichi, Mizuho was his brother Shohei's girlfriend, and Yuichi hypothesized that she might still have feeling for his brother, making himself a bit of a Replacement Goldfish). Kawamura also has been spurned twice by the objects of his affections. Before the start of the series Nano, Wataru's girlfriend who wanted matching rings but he didn't (and more significantly, he was the one who called off their relationship).
- The Beard: On a situation during a school festival, Karin was asked to stand as Yuichi's beard.
- Belligerent Sexual Tension: Yuichi is intentionally something of a Jerkass to Wataru to hide his feelings, and Wataru is too much of a spitfire to take it lying down.
- Big Brother Instinct: Shohei towards Yuichi. Masaaki towards Asaka, although this case is little brother complex. Masaaki is even described as such in-story.
- Cannot Spit It Out: Yuichi Kazuki. In contrast to Wataru, who at least tries to take a fairly direct approach once he figures out his feelings, Yuichi basically has to have the truth pried out of him. Only after a near-confession from Wataru does he even begin to indicate his true feelings, and only after some meddling from his cousin and Wataru's actual confession does he manage to say anything about it.
- Childhood Marriage Promise: Yuichi's five-year-old niece Takako thinks that the ring Wataru gives her in a moment of weakness is an engagement ring. Yuichi is not very happy when he finds out.
- Clingy Jealous Girl: Miho during the first lost (actually stolen) ring incident. She gets better once she realizes that Wataru really loves Yuichi.
- Cool Big Sis: Touko, Yuichi's cousin and Karin, despite being Wataru's younger sister, both qualify as they're much more mature than the boys.
- Contrived Coincidence: The ring-switching incident can be testing on Willing Suspension of Disbelief for some.
- Distaff Counterpart: Miho is said to be a female version of Yuichi due to her beauty and behaviour at school. To further underscore the similarity she develops feelings for Wataru.
- Earn Your Happy Ending: From the beginning to the end for the protagonists. This may well be the subtitle of the novels. On a side note it seems that Yuichi's brother Shohei had to scheme and plot his way to obtaining his wife Kirie.
- Easily Elected: Kazuki got the most votes student council president despite not even running. The votes were declared invalid and the runner up was elected instead. Despite this, the president is actually his friend and allows Kazuki to have a key to the office.
- Ephebophile: Mizuho dated Yuichi, a teenage boy eight years her junior. The fact that said boy is her ex's brother might have something to do with that.
- Fangirl: Yuichi has an army of them. They even are organized to some degree. Mai Tachibana though takes the cake.
- First-Name Basis: Yuichi quickly starts calling Wataru by his given name, even before they get together. Wataru is more reserved and even in the end of the series has trouble calling Yuichi by his first name.
- Forceful Kiss: Asaka to Wataru, twice. Yuichi also does this in a fit of jealousy.
- From the Mouths of Babes: "Even at five, a woman can tell a joke kiss from a real one".
- Gossip Evolution: In the first half of the novel and the manga, the fact that Yuichi asks for direction to the school of Wataru's sister is somehow mutated into Yuichi going out with her. The trope is played with in that Wataru intentionally does nothing to dissuade this rumour to avoid another one concerning him and Yuichi wearing matched rings.
- Harmful to Minors: Played for laughs. Wataru is rather disturbed by the fact that Yuichi has no compunction about kissing him before children. Shohei is certainly not happy to hear from his daughter that his brother kisses a male lover in front of her.
- Hidden Heart of Gold: Yuichi puts on a jerk act to hide his crush on Wataru. Kind of played with, as everyone else thinks he has a very obvious heart of gold.
- Hopeless Suitor: Asaka, Miho for Wataru. Mai Tachibana and the rest of the fangirl horde for Yuichi.
- I Kiss Your Hand: Yuichi kisses Wataru's ring, which confuses Wataru to no end given Yuichi's rude behavior up to that point.
- I Was Just Passing Through: Yuichi's explanation for his helping Wataru in the library, given his jerkish treatment of the latter up to that point.
- Jealous Romantic Witness: Wataru watches Yuichi walk arm-in-arm his Touko while she calls him her "favorite guy" and immediately decides that he's in love with Yuichi and also that he needs to give up on him. After finding out she's his cousin...he still thinks she's a more viable love interest than he is.
- The Lancer: Kawamura to Wataru. He snarks about the latter's moonstruck behaviours since falling in love and tendency to Wangst or do irrational things, but wholeheartedly supports his friend's love.
- Likes Older Women: Yuichi. Before the start of the novels he dated a woman named Mizuho who was eight years older than him.
- Love at First Punch: Masaaki fell for Wataru's sister Karin after she verbally slapped him for bullying her brother.
- Love Dodecahedron: The novels feature a milder than usual one, but both Yuichi and Wataru have other suitors.
- Love Hurts: Wataru has a few hellish days in the fourth novel and the beginning of the fifth one due to a misunderstanding.
- Lost Wedding Ring: His ring isn't a wedding ring, of course, but Wataru still manages to have a Lost Wedding Ring plot in the novels when a jealous girl manages to get her hands on his and essentially holds it for ransom. And then it happens again when Asaka contrives to steal Wataru's ring at the end of the penultimate novel. The latter case is arguably subverted when Wataru, having learned a few things from the previous experience, decides that he should straighten out his more serious problems with Yuichi rather than worry too much about a souvenir like the ring.
- Love at First Sight: How Yuichi fell for Wataru When She Smiles...or he, in this case.
- Love Makes You Crazy: Yuichi is a mild example, but falling for Wataru certainly does a number on his ability to behave rationally... which stands out since he's otherwise very socially adept.
- Man of Wealth and Taste: Shohei. All of Yuichi's family is wealthy.
- Not What It Looks Like: Wataru thinks Yuichi's cousin Touko is his girlfriend after seeing them together in the park on Yuichi's birthday.
- Perspective Flip: This nice fanfic
tells the story (of the manga) from Yuichi's POV. - Poor Communication Kills: Goes hand in hand with Cannot Spit It Out.
- Precocious Crush: Takako, Yuichi's five year old niece, towards Wataru.
- Princely Young Man: Both Yuichi and Asaka are of Prince Charming variety, though Wataru knows too well that in Yuichi's case, it's very much a facade.
- Relative Error: Zig-zagged. When Wataru sees Yuichi walking with a lovely young woman for whom he expresses open affection, he assumes the two of them are dating. He subsequently learns that she's Yuichi's cousin... which does nothing whatsoever to reassure him, since the relative lack of stigma Japanese culture places on Kissing Cousins means that she's still a more acceptable partner for Yuichi than he is. Nevertheless, there's nothing romantic going on between the two.
- The Reveal: The plot of the first novel revolves around the apparently uncanny coincidence that Wataru and Yuichi wear identical rings, and Yuichi's confusing behavior towards Wataru after their rings are accidentally switched. It's only at the end of the novel that Wataru learns the truth: Yuichi had fallen in love with him and commissioned his ring to be identical to Wataru's.
- Romantic False Lead: In the novels, Masanobu Asaka, a peer of Yuichi's who develops a crush on Wataru. And briefly Miho. Also Mizuho, an ex of Yuichi who seems to still have feelings for him.
- Secret-Keeper: Toko and Karin are the first to know of Yuichi's and Wataru's relationship. Also Kawamura, Wataru's best friend.
- Seme: Yuichi. Different from the usual Seme somewhat in that he is a severe case of Cannot Spit It Out.
- Settle for Sibling: In the first novel Yuichi taunts Wataru with this. He considers going out with Karin since he does not think that he can have Wataru. Fortunately a sound slap from Wataru gets that idea out of his head.
- Sick Episode: Yuichi in the fourth novel and Wataru in a side story taking place between the first and the second novels. Both tried unsuccessfully to hide the fact from the other, and got exasperated when their partner did not tell them about being sick.
- Slap-Slap-Kiss: Wataru and Yuichi's relationship is this. More kiss than slap after they get to be together though.
- Smug Snake: Shohei in his schemes to separate Yuichi and Watatu comes across as this. He also has some shades of a Trickster Mentor.
- Stepford Smiler: Wataru believes Yuichi to be one after experiencing the latter's nasty side. Maybe he is not far from the truth if one buys the theory that under the "prince" façade, Yuichi does not actually care about anything or anyone, and just goes along with people's expectations because he does not have anything else to do (until he finds the love of his life, that is).
- Strong Family Resemblance: Wataru and his sister Karin are practically genderbent versions of each other. Shohei almost mistakes Karin for Wataru at a school festival.
- Theme Naming: All novels have "ring finger" or "hand" in their titles.
- Tsundere: As said above, Yuichi Kazuki. A rather weird mixture between Type A and Type B. Yuichi is nice to everyone else but does not hesitate to belittle Wataru, the boy for whom he has strong feelings, even without provocation. On the other hand, he can be helpful and sweet (while still teasing and condescending) to said boy. Complicated guy.
- Title Drop: From Yuichi, at the end of the first volume when he and Wataru finally get together: "Let them say what they wanna say, only our ring fingers know the truth."
- Uke: Wataru, of the feisty variety.
- What Beautiful Eyes!: Yuichi Kazuki has nice eyes as part of his good looks but it's Wataru's striking dark saucer eyes that often get commented on by other characters in-story.
- When She Smiles: How Yuichi fell for Wataru—he returned Wataru's ring the first time he lost it from a distance, before they met, and Wataru's smile made him fall in love.
- With This Ring: The whole "couples wear matched rings" fad is central to the plot of the initial storyline, and while the fad mostly seems to go away later in the Light Novels, Yuichi and Wataru's rings retain their personal significance.
- Yaoi Fangirl: Takako seems to be shaping up to this.
