[[caption-width-right:350:Matsuoko and Tooru]]
[[caption-width-right:320:From the right: Tooru, Atori, Hikaru, and Yuki ]]

The Rules Universe consists of a series of {{yaoi}} stories created by KanoMiyamoto which mainly revolves around Hikaru, his love interests, and friends. Hikaru's high school friend and love rival Ryuu debuts in Please, while Hikaru himself debuts in Kiss. Hydra and its doujinshi revolves around Ryuu, Hikaru, and Hitomi and their high school years. Lovers and Souls covers the story of Hikaru's prostitute friend Tooru and Tooru's sempai, Matsuoko. Rules and its doujinshi focus on Hikaru, Yuki, Tooru, and Atori.

As of 2011, the Rules series Timeline is as follow:
* Please (chapter 5)
** Kiss
** Kiss After
** Skies
* Hydra 1+2+3+4
* Hydra 5+6
** Heavenly
* Hydra 7+8
** Blue Film
* Hydra 9+10+11
** The Days Before
** Real Thing
** Hello Again
* Lovers and Souls
** Fragile
** Vanity
** Dreamer's high
* Rules volumes 1 & 2
** If Winter Comes, Can Spring Be Far Behind?
* Rules volume 3
** Song Birds
** Another Day on The Planet
** Another Rules Story
** Double Trouble
** Overload

From [[http://www.liquideros.com/project_timeline-rules.html Liquid Eros]]

Hydra: When Ryuu transfers to Hitomi's school, he leaves an immediate impression on him. Curious about rumours of a full-scale tattoo on Ryuu's back, Hitomi starts getting closer to him. Before long, the friendship and fascination Hitomi feels for Ryuu start developing into more, but before he has a chance to come to terms with his feelings, Hikaru appears on the scene.... and he has his eyes set on Hitomi.

Lovers and Souls: Tooru is a young model who becomes a gay prostitute because he doesn't care enough about himself. However, he's starting to fall for his sempai. Can Matsouko save him?

Rules: Yuki, a high school student, is confused about his sexuality. He meets Hikaru in the sleazy gay district, and sleeps with him. They begin to play at being lovers, but Konoe's heart belongs to Atori, his friend and classmate. Can Yuki come to terms with his sexuality and reveal his feelings to Atori, and where do Hikaru's true feelings lie?
!!The series contains examples of:
* AccidentalMurder: Part of [[spoiler: Ryuu's]] past, and responsible for his {{Angst}}
* AllGaysArePromiscuous:
* AnchoredShip: [[spoiler: Hitomi and Ryuu]]. They probably got together. Probably.
** [[{{ReunionKiss}} Reunion Hug]]
* TheAtoner: Zigzagged with Itou.
* BiTheWay: Everyone except Yuki it seems, something which is lampshaded by him.
* BoysLove
* CannotSpitItOut:
* ChekhovsGunman: Hikaru in the beginning of Hydra. He starts as a GenericGuy [[spoiler: in the GangOfBullies]] and is not until a few chapters later that we learn his name.
* ClassReunion: Lampshaded by Satou when Hikaru, Ryuu, Hitomi, and her reunite six year after high school. Hikaru invited Itou, but he declined.
* {{Coming Out Story}}
* [[spoiler: DroppedABridgeOnHim:]] Matsouko.
* {{Fetish}}: Ryuu's tattoo, especially for Hitomi.
* FriendsWithBenefits: The relationship between various of the characters with varying degrees of success.
* GangOfBullies: Unique in that [[spoiler: Hikaru was pat of it]]
** The leader, [[{{Jerkass}} Itou]] bullies the main characters because he is a StalkerWithACrush of Satou.
*** He pulls a IfICantHaveYou on her, which is used as an excuse for her [[{{PutOnABus}} Put On A Plane]] status.
* {{Gayngst}}
* GenderBlenderName: Hitomi is a guy.
* GoodScarsEvilScars: Hitomi by his eye due to a motorcycle accident that happened before the start of the story.
* HairstyleInertia: Averted. Everyone changes hairstyle and sometimes hair color as time passes on.
* HookerWithAHeartOfGold: Male example with Tooru.
* IWantMyBelovedToBeHappy: [[spoiler: Hikaru]] for [[spoiler: Hitomi]]
* LookingForLoveInAllTheWrongPlaces: Hikaru to a certain extent.
* LoveTriangle: Apart from the love triangle in Hydra, there is a nice romantic square in Rules.
* MayDecemberRomance: There's a 10 year difference between Hikaru and Yuki.
* RedLightDistrict
* RomanticFalseLead
* SecondLove: Yuki for Hikaru and vice versa; Atori for [[spoiler:Tooru]].
* {{Seme}}/{{Uke}}: Averted, in that you can't tell who is which and that once in awhile they switch roles.
* TheSmurfettePrinciple: Satou is the only female with some importance in the Hydra manga. That is until she was [[{{PutOnABus}} Put On A Plane]]
** [[{{TheBusCameBack}} The Plane Came Back]]: She came back for a reunion with Hitomi, Ryuu, and Hikaru at the end of Hydra.
* ThreeAmigos: Hitomi, Ryuu, and Satou somewhat have this dynamic for part of Hydra until Hikaru was introduced and Satou was [[{{PutOnABus}} Put On A Plane]].
* UnrequitedLove
* {{Yakuza}}: None of the characters are Yakuzas but Ryuu's father, who is a tattoo artist for the yakuza, gives Ryuu a tattoo which leads other students to believe that he belongs to the yakuza.
* YourCheatingHeart