Legend of the Five Rings, also abbreviated as Lot5R or simply L5R, is both a tabletop RPG and a CCG set in the same universe. The setting, a land known as "Rokugan", is a sort of fantasy version of feudal-era Asia, mainly based on Japan, and players typically take on the roles of members of the samurai social class (which, despite the name, also includes noncombative diplomats, courtiers, and faux-Taoist sorcerers as well as the stereotypical samurai warriors). Despite all this, the game is not widely regarded as particularly weeaboo, and discussions about it are generally calm, albeit very infrequent. Its metaplot, based on the results of the CCG tournaments, is both praised and loathed by fans.
Over 9000 years ago, Lord Moon and Lady Sun appeared on the relatively shapeless world and gave it form. This world was created by Nothing (with a capital N), it all being very mystical and shit.
Lord Moon started chasing after Lady Sun's skirts until one day he caught her, and when one anthropomorphic representation of a celestial body loves another anthropomorphic representation of a celestial body very much... Ten sprogs she borne him: Hida, Doji, Togashi, Akodo, Shiba, Bayushi, Shinjo, Fu Leng, Ryoshun, and Hantei.
As it tends to happen in these stories, Lord Moon decided that eating his own children was a very good idea. Lady Sun obliged, but got him to drink some poisoned sake after each child, thus making Lord Moon drunk as hell and letting one child (Hantei) escape. Hantei would train to become a badass and after another >9000 years, he called his old man out. Epic battle ensued in Heaven, and all of his siblings escaped except for Fu Leng, who ended up crashing into the Earth... and Ryoshun... Ryoshun died.
The children descended into the Earth, became mortal, and had a tournament to decide who should run the world: obviously, Hantei won and became the Emperor. The rest of his brothers formed Clans out of the scattered humans living in Earth, and Rokugan, the Emerald Empire, was formed.
And Fu Leng? Obviously he got mightily pissed at his siblings forgetting about him, so he took over what would be later known as the Shadowlands, built zombies, trolls, oni, and other monsters and sent them to killfuck the Emerald Empire. For all of their combined badassery, Hantei and company couldn't put up a fight and when they were about to die, a monk called Shinsei showed up and promised Emperor Hantei that he could take out Fu Leng with no problem. Since the guy wrecked Hantei's bodyguards unarmed, he let him take seven warriors (one per clan) and go.
Fu Leng's armies crumbled before Hantei's forces not long after that, but only one of the party returned: the Scorpion samurai, who faked her own death not long after. The Clans generally got along after that, and a thousand years of peace (save the odd Clan war, uprising and whatnot) followed.
Then the PCs showed up.
 The Clans
The Crab, founded by the Kami Hida, are Rokugan's primary defense against the Shadowlands. They maintain and defend the Great Carpenter Wall
of China. They are rude, dirty bullies that care little for Rokugan's etiquette, but they are tough as nuts and honest about things. These are necessary qualities when you are fighting with insidious and alien evil every day.
- Crab Hida Bushi are experts in reducing damage, since they get beat on all the time by supernatural opponents. They prefer heavy weapons, to give as good as they get.
- Crab Hiruma Bushi are scouts - they are good at using the Attack Stance and generally being quick survivalists. Good in a skirmish.
- Crab shugenja specialize in magic that focuses on and smacks down anything tainted by evil.
- Crab courtiers will haggle, badger, intimidate, and then threaten to get their way.
"The Left Hand Of The Emperor." All emperors had Crane girls for wives for a long while, so Doji's Clan has had heavy political influence in Rokugan since times immemorial. They have set the rules for social interactions both in court and in daily life for centuries. They are very wealthy, very proud, and they also dig the white-haired pretty boy look.
- Crane Kakita bushi are duelists, with perfect form and gorgeous to watch in action.
- Crane Daidoji bushi are surprisingly tough, especially for Crane, and excel at being bodyguards.
- Crane shugenja specialize in non-lethal effects, and crafting works of beauty and wonder.
- Crane courtiers will trade favors and politically out-maneuver their opponents.
The Dragon are the most reserved of the Clans. They mostly keep to themselves in their mountain retreats, and most strangers never quite know what to make of Togashi's Clan. Of all the Clans they value independent thought the most, and come the closest to non-conformists -- duty is still paramount, but it can be up to you how to fulfill it. They have crazy tattooed monks that breathe fire and piss heroin (one of these may be a lie).
- Dragon bushi are known for their two-weapon style, which other clans find a little weird.
- Dragon shugenja are alchemists, using materials to enhance themselves or others.
- Dragon courtiers are unconventional, which makes people uncomfortable in the courts, but they can see right through the obfuscations and misdirections that form political combat. They are the closest anyone in Rokugan comes to a proper detectives, and many of them work as magistrates rather than courtiers, though the legal system finds their focus on evidence and deduction really weird.
- The Togashi Monks, which are effectively a family unto themselves, are strong at unarmed combat and are extremely modifiable through a variety of tattoos that grant them further powers.
"The Right Hand of the Emperor." Soldiers and generals per excellence, the Lion are a very powerful Clan. They've been at this for dozens of generations, which makes them paramount experts in military matters, but somewhat unwilling to listen to new ideas. They also don't play well with other samurai that aren't as "RAH RAH HONOR BUSHIDO" as they are. Nonetheless have the Emperor's ear when it comes to military matters. Akodo's people are crazy honorable, but that doesn't make them nice guys.
- Lion Akodo bushi are experts in precision, striking exactly in the right place at the right time.
- Lion Matsu bushi are berserk warriors who excel at using the Full Attack stance, which lets them hit hard and accurately but leaves their defense wide open.
- Lion shugenja can always communicate with their ancestors; Lion clan doesn't have to wonder if their predecessors would approve of their actions, they can just ask, and they have centuries of wisdom to advise them. They're also there to help glue the warriors back together with healing and support magic.
- Lion courtiers would never engage in the duplicity and insincerity that can get one ahead in the arena of politics. Instead they rely on precedents and storytelling to demonstrate their path is the correct choice.
Founded by a half-Lion half-Crab who had been passed over for leadership of the Crab Clan, the Mantis claimed to be the oldest minor Clan in existence, something that was disputed by the Fox. At the Second Day of Thunder, when the clans united to fight Fu Leng, the Mantis daimyo demanded that the major clans recognized his contribution by promoting the Mantis and their allies to the status of a Major Clan, the Mantis absorbing their good buddies. Generally reckoned as traders and suspected of piracy.
- Mantis Bushi are either sailors, and thus good with unstable surfaces and using unconventional "peasant" weapons, or lethal archers (the former Wasp Clan)- generally of the "won't miss" variety.
- Mantis shugenja are really good with storms. Unless they are priestesses of the Sun.
- Mantis courtiers handle trading and not-so-subtle suggestions of how you are better being allied to them than letting them ally to another clan. They use their wealth as a political blunt instrument, and, if that fails, actual blunt instruments as political blunt instruments.
Shiba's crew are devout followers of Rokugan's two religions - the old-school Fortune worship and Shinsei's "New Path". Their shugenja (the aforementioned faux-Taoist sorcerers) are some of the most powerful of Rokugan, but the Clan doesn't like warring so they are not as powerful as one would think.
- Phoenix bushi are known for having surprising insights on the battlefield to take advantage of opportunities others would miss. They favor polearms and spears, and have their hands full working as bodyguards for their shugenja.
- Phoenix shugenja are the most powerful and numerous in the Empire, which makes them a little arrogant, particularly the Isawa. The Isawa shugenja can excel at any element you like, while the Agasha can power spells with different elemental types than the ones they typically specialize in.
- Phoenix courtiers aren't ones for playing games, and they will prove their point by citing academic or scholarly texts or arduously logical conclusions.
The Scorpion Clan do the dirty-work of the Emperor. Their gimmick is knowing stuff... about you... that you'd prefer was kept secret. Since Rokugan puts a lot of importance in public perception, honor and shame, this gives them a great edge over (and the silent hatred of) most other Clans. Woe to the players that have Bayushi fanboys for GMs.
- Scorpion bushi specialize in dirty tricks and lightning-fast strikes.
- Scorpion shugenja are really into illusion and deception magic.
- Scorpion courtiers are masters of blackmail. The only thing worse than having one as an enemy is having one as an ex-ally.
- Scorpion ninjas are what you'd expect, so long as you expect actual spying and wetwork instead of goofy black-pajamas shenanigans.
The Spider clan was founded in more modern time by Daigotsu, and claims Fu Leng as their patron founding Kami. Their expressed goal is to rule the Empire. The Spider initially begin as a secret conspiracy, then progress into a "ronin group" pretending to be virtuous, and then later into a full Clan after they save the Empire from total destruction by the hands of the Demon godess Kali-Ma.
- Spider bushi are all about overwhelming force- they hit hard, and can weaponize Shadowlands taint to hit even harder and take more abuse.
- Spider shugenja are Maho-tsukai, and specialize in mitigating the taint caused by their dark spells. When the Spider become a Great Clan, most of their shugenja give them the finger and bail.
- Spider courtiers are subversives, sowing dissent and turning people towards darkness while moving blame away from them.
- Spider ninja are corrupted minions of the Shadow Dragon with strange powers. They make for excellent assassins and but rarely have any real personality.
Shinjo took her men with her far from Rokugan after Fu Leng died, and they have returned to the Empire after 800 years of wandering. A bizarre mix of Mongol, Arab and Japanese influences, the Unicorn are strangers in the Emerald Empire, but they know some tricks the other Clans don't, and they have the best cavalry around.
- Unicorn bushi are masters of mounted combat; everything they do is done better from horseback. They prefer to use exotic weapons that other clans don't touch, like lances or scimitars. Come in Moto and Utaku varieties, depending on how much of a gaijan you want to be.
- Unicorn shugenja work mostly with movement/travel magic, and communing with animals (especially horses, duh).
- Unicorn courtiers are mediators, acting as an impartial outsider to help resolve conflicts and thus indebting both parties to Unicorn clan.
- Minor Clans
The Minor Clans are those who do not descend from the Children of the Sun and the Moon. They are typically created as a reward for samurai that performed major deeds in the name of the Empire. The most powerful of these used to be the Mantis Clan, who live in islands south of Rokugan and have the greatest navy in the Empire, but have been promoted to a major clan and absorbed several other minor clans in the process.
 The CCG
The whole rigamarole started as a collectible card game. The "one-true setting" of Rokugan is described in plot arcs that correspond to CCG releases, and the outcomes of turning points in the plot are decided at annual or semi-annual CCG tournaments.
The RPG's history follows the CCG history closely until the 4th edition (released 2010).
The CCG has four ways of winning a match. The first and most common is Military, where one player destroys all four of another player's provinces. The next two are Honor and Dishonor, in which you either start your turn with a family honor of 40 or higher, or your opponent ends their turn with a family honor of -20 or lower. The last way of winning is Enlightenment, where you have in play all five of the Elemental Ring cards, brought into play by their own effects.
 The RPG
Characters in the L5R RPG are usually samurai ("knights," but not necessarily sword-swingers) either belonging to one of the Clans or lordless ronin. Rokugan is a troubled land, besieged both by the threat of the Shadowlands and the constant jockeying for supremacy between the Clans. Life is very ordered for PCs, so "LOL!randum XD" players will see their characters cut down quickly; Rokugan has little tolerance for non-conformists. Typical excuses for parties working together are: having all PCs be part of one Clan and its allies, having them all participate in one of the Winter Courts (social campaigns involving the Emperor and other bigwigs) or making them all Emerald Magistrates, a free-roaming force of samurai troubleshooters for the Empire.
Depending on the edition, the system uses D10s or D20s. That explode.
The RPG is noted for, among other things, having a deep set of rules for 1-on-1 duels. Is That Guy giving you trouble? Is he not a Crane? Challenge him to a duel.
Legend of the Five Rings fourth edition (the current edition) has a fairly strong community on the sup/tg/ IRC server (irc.thisisnotatrueending.com). Players looking for games, chat, or anything else related to the RPG should check out #L5ROOC and/or talk to KingGheedorah, who moderates the channel and is currently running over 9000 L5R games.