[[quoteright:250:http://static.tvtropes.org/pmwiki/pub/images/not_that_secret_2748.jpg]]
-> '''Yuuichi''': "Lover to paramour, huh? A drop in the ranks, I guess."
-> '''Iori''': "You haven't risen or dropped. I have always, always loved you...since the day we met and now. [[ExactWords I'll sacrifice anything.]]"

A one-volume BoysLove manga by writer Gotoh Shinobu and artist Maruya Kae. Yuuichi was orphaned at a young age, with his only family connection being his strange uncle Kyuusai who is famous for writing mystery stories. The story begins when his relationship with his [[ChildhoodFriendRomance childhood friend]] Iori is challenged when he finds out Iori, the [[ImpoverishedPatrician Hanayashiki heir]], is marrying into the [[NouveauRiche Yonekura family]] to restore the family's fortunes. Though Iori assures Yuuichi that he will always love him, Yuuichi privately doubts he'll ever be allowed to meet Iori again.

The marriage day gets quickly overshadowed by a series of strange incidences related to Yuuichi's RecurringDreams. The final wedge is driven between the lovers with Kyuusai's revelations of Yuuichi's real heritage and nature, which suggests their love is not what it seems, with only one of them destined to survive it.

----
!!''The Secret Agreement'' provides examples of:

* AltarTheSpeed: Yuuichi's uncle sees Iori leaving a famous tearoom with his family and fiancee and tells Yuuichi about it. When Iori turns up later the same night, he confirms it was an omiai[[note]]meeting of a pair of marriage candidates[[/note]] and casually mentions that the wedding is the ''next day''.
* ArrangedMarriage: Iori doesn't see his marriage as an obstacle to his relationship with Yuuichi simply because it's always been a fact of life as the heir that his family would arrange a marriage for him no matter how he felt.
* AwfulTruth: Kyuusai reveals to Yuuichi that he is from a powerful clan that steals other people's life force, and that neither he or his boyfriend love each other, it's just a delusion between predator and prey that makes it easier for Yuuichi to steal Iori's life. Yuuichi is understandbly horrified.
* BarbieDollAnatomy: A glaring example occurs when Iori walks all over Yuuichi's apartment naked, [[TropesAreNotBad but explicit detail probably wouldn't complement the style anyway]].
* BeCarefulWhatYouSay: Iori telling Yuuichi that he loves him more than anything and would sacrifice anything for him. This is romantic until Kyuusai reveals to Yuuichi that his destined prey will naturally [[HarsherInHindsight offer his life]] for him to take.
* BigWhat: In the middle of having sex Iori mentions that his wedding is tomorrow. This is probably the only response Yuuichi could have.
* {{Bishonen}}: Being a BoysLove series all the male characters qualify by default, but in-story Iori's unearthly beauty is acknowledged by the entire community.
* BlessedWithSuck: Kyuusai tries to convince Yuuichi of the benefits of being a clan member but Yuuichi is understandably more preoccupied with the fact that he may not actually love his lover and will kill him (and Iori will give his life willingly, because he is also not in love but under a delusion).
* BlueBlood: The Hanayashiki family. The Yonekura family has some status in society, but their assets are more their wealth.
* CaughtTheHeartOnHisSleeve: Despite how much they love each other Iori is unsuccessful in his appeal because Yuuichi can't bear the consequences of staying together.
* ChildhoodFriendRomance: Yuuichi and Iori have had an intense connection since childhood which naturally developed into a relationship as they got older. It's later revealed to be [[AwfulTruth not what it seems]] though.
* DreamingOfThingsToCome: Yuuichi's unpleasant RecurringDreams are actually his supernatural side being awakened.
* FateDrivesUsTogether: Not a very nice example, as Yuuichi's uncle states the reason Iori has such a connection to Yuuichi is not because he loves him but because Yuuichi is built to steal Iori's life energy and Iori exists only to be consumed.
* IAmWho: Yuuichi thinks his uncle is making up the whole life-stealing story about their family, but unfortunately the evidence isn't in his favour.
* IJustWantToBeNormal: Yuuichi would rather have not found out his [[TomatoInTheMirror tomato]] status.
* ImpoverishedPatrician: Part of why Yuuichi's friendship with Iori is tolerated by Iori's family is because they are steadily declining in wealth and Yuuichi sells valuable antiques for them discretely.
* InterClassRomance: Iori is the only male heir to an [[ImpoverishedPatrician increasingly poor]] but noble family and set to marry into a wealthier but less respectable family for their mutual benefit. Meanwhile his actual [[ChildhoodFriendRomance lover]] is a former StreetUrchin and fears if Iori marries he'll never see Iori again because the family won't need him to quietly sell off their possessions anymore (the only reason their friendship was tolerated in the first place).
* IWillFindYou: Iori has always been able to sense where Yuuichi is, and promises that as long as Yuuichi is running from him he will follow behind until Yuuichi gives up.
* LongHairedPrettyBoy: Iori.
* LossOfIdentity: While Kyuusai treats Yuuichi's blood awakening as a finding of identity, Yuuichi feels like his identity and meaning have just been wrenched away.
* LoveWillLeadYouBack: Inverted. Iori isn't worried about Yuuichi running away, because his own love will always lead him towards Yuuichi.
* MyOwnPrivateIDo: Inversed when Iori conducts his own private "I don't" by only pretending to drink from the marriage cup that is part of the wedding ceremony. His sister, who is under the illusion that he just doesn't like taking food from people who aren't her or their mother, notices it and laughs about it privately with Yuuichi, who recognizes it for what it is--Iori symbolically indicating that even if he's married, his love is only pledged to Yuuichi.
* NobilityMarriesMoney: This is the idea behind the ''very'' sudden wedding between Iori and Hisayo. The well-respected Hanayashiki family arranges a marriage with the wealthy Yonekura family to restore their fortunes. The Hanayashikis are guaranteed financial security and the Yonekuras benefit from the Hanayashiki reputation. The groom stays for the ceremony but ends up running away that night, chasing after his lover. The remaining family members seem to get along, however, and still consider it a legitimate alliance.
* OddCouple: Yuuichi is down to earth and realistic while Iori is impractical, otherworldly, and has very scattered attachments to actual things. On top of this there is a large wealth and class gap between them. They aren't quite a case of OppositesAttract, but in-story Yuuichi remarks to himself how they are an unlikely pair.
* ParentalAbandonment: Yuuichi lived on the streets and basically raised himself. His uncle isn't even his real uncle.
* PleasePutSomeClothesOn: Yuuichi has trouble getting Iori to put on clothes again after he's taken them off and basically has to dress him himself. He is half-frustrated, half-bemused that Iori just doesn't get [[DistractedByTheSexy why]].
* ThePromise: Iori makes quite a few, but they all unwittingly take on a sinister bent. Yuuichi also tries to go back on his own promises to Iori to protect him.
* RealMenHateSugar: At the start Kyuusai rejecting all sweets ''seems'' like he's subtly teasing Yuuichi for being unmanly, but it turns out he was being literal and sugar actually kills people from their clan.
* TheReveal: No, you don't love each other, Yuuichi, he's just your prey.
* RightThroughHisPants: Yuuichi still has his pants mostly on in the chair sex scene.
* [[RunawayBride Runaway Groom]]: Iori actually does get through the ceremony, but immediately afterwards decides to chase Yuuichi across the world, leaving his bride and his mother rather surprised.
* SelfMadeMan: Yuuichi, being an orphan, built his business on his own. Even when he found out he had an uncle he didn't go to him for anything he needed.
* ShelteredAristocrat: Yuuichi regards Iori this way because of his lack of worldliness, and while he doesn't like it he outright states that the marriage will be a good thing for Iori since Yuuichi doubts Iori could live a poor life.
* SlidingScaleOfBeauty: Iori is world-class. After meeting him for the first time, Kyuusai later teases Yuuichi about their relationship saying "I understand you're the type attracted by looks."
* StarCrossedLovers: As if being gay lovers from very different class strata ca. 1920s-30s wasn't enough, it turns out that if Yuuichi doesn't take Iori's life, he will die instead. There is really no way to win.
* StreetUrchin: Yuuichi as a child, having been orphaned in the war.
* SweetTooth: Iori has one, and Yuuichi is treated as if he does by his uncle because the fact that he can eat sweets at all is so significant.
* ThroughHisStomach: "It only took three-quarters of a mitarashi dango to make you mine."
* WhatNowEnding: The story ends pretty abruptly, with readers left to assume that Yuuichi will probably end up dying, and several questions are left hanging (Was their love genuinely more than a delusion? What is Hisao's deal?)
* WhyCouldntYouBeDifferent: Yuuichi is initially abandoned for appearing to be a {{muggle}} but then assigned a clan guardian to watch over him in case he starts showing signs of change. In perhaps an inversion, despite his uncle's congratulations when his supernatural side finally awakens, Yuuichi is [[AwfulTruth horrified at becoming "normal"]].
----