The history of House Yato of Draconis III is a long and gloried one, filled with battle honors stretching over more than ten millennia. The original colonists of Draconis III mostly originated from Nippon of Old Earth, their many ships and arks landing on Draconis III and its nearby worlds, thus seeding a population in the Draconis Sector that tended toward a worship of the Kami. The earliest settlers survived the monstrous inhabitants of Draconis III's many forests and seas - which they term Ayakashi - by piloting massive bipedal armored suits to drive them off. From the titanic serpentine Orochi and their kings, the nine-headed and nine-tailed Yamata no Orochi to the leviathan Bake-Kujira that dwelled in the depths of the oceans to the gargantuan, amphibious Ryuu. These bipedal armored suits later formed the basis of the numerous Knight Houses, massive formations of Knight walkers that marched in defense of the colonists against the behemoths that haunted Draconis III. Each Knight House was commanded by a Daimyo, a warlord who claimed to possess the pinnacle of courage, virtue and honor, but no matter their allegiance, the Draconians came to worship the sun. They believed that the Sun Goddess would deliver a savior to them, to unify the planet and bring unprecedented prosperity.
It was this faith in the Sun Kami and the adamantine valor of the Knight Armors that saw them survive the Age of Strife and the horrors of the Old Night. The Ayakashi and many twisted denizens that emerged from the netherworld, which the Draconians termed Jigoku (or the Warp in low Gothic), were banished back to their foul realm, the Knights crushing them underfoot and reaping them with their gigantic chainswords and burning them with hi-tech weaponry. The Men of Iron who rose against humanity were quickly culled, and the Knight World of Draconis III plunged into feudalism, with each Daimyo staking out his own private domain and commanding armies of Knights.
Eventually, the Warring Era was ended by the tactical ingenuity of a single Daimyo - Yato Yasutaka of House Yato. Yato Yasutaka led several hundred Knights in over several dozens of campaigns to isolate and crush each of his rival houses one by one. He was a shrewd diplomat, able to absorb lesser Houses into his own and forge powerful alliances - persuading Takeda Kenji of House Takeda and Uesugi Fuutarou of House Uesugi to join him in uniting the whole of Draconis III under his rule. Within four decades, he successfully emerged the supreme power on Draconis III, tying the fates of the proud House Takeda and the skilled House Uesugi to his House Yato through marriage politics or promises of glory, and subjugating the powerful House Oda, the patient House Tokugawa and resilient House Akita. Yato Yasutaka would take on the mantle of the Shogun, the ruler above all the other Daimyos, the Draconian equivalent of the High King.
With the Mechanicum's assistance, the ranks of House Yato and their subordinate Knight Houses were furnished with many new Knight suits, including Cerastus patterns. While the majority of Knight armors still composed primarily of the Questoris chassis, the Knight Houses of Draconis III also received a substantial number of Cerastus chassis, as well as a few Acastus chassis. Armiger class Knights, including Armiger Knights Moirax, and Dominus Knights expanded their roster, and when Legio Draconis was founded in Draconis IV, an entire branch household of House Yato was pledged as a vassal Knight House to serve the Titans of the Dark Dragons. Thus House Kanda was formed, and they received exotic Knight armors not seen in many Houses, such as Questoris Knight Stryrix and the deadly Cerastus Knight Atrapos.
With Draconis IV's specialization in plasma weaponry, it is no wonder that Dominus Knight Castellan became one of the most prevalent Knights among households in Draconis III. Their expertise in laser weaponry also meant that House Yato and their branches have an unusually high number of Questoris Knights Preceptor, though Questoris Knights Errant and Questoris Knights Crusader are fairly common. The Armiger Knights Moirax are armed with exotic weaponry, such as volkite veuglaires, though Armiger Warglaives are also fairly common, with them being the preferred Armiger variant among the warriors of House Yato, desiring a close combat weapon. The sword remains a sacred symbol to the Draconians, so they prefer Reaper chainswords (or Reaper chain cleavers) to Thunderstrike Gauntlets, and the Cerastus shock lances of Cerastus Knight Lancers - the most common Cerastus pattern for House Yato - are modeled after the naginatas of old warriors atop horseback.
When Horus Lupercal turned against the Emperor, the Knight Houses of Draconis III declared their loyalty to the Emperor, who they viewed as the descendant of their Sun Goddess, Amaterasu. The Shogun was believed to rule as the Emperor's proxy, and the Draconians developed a fanatical belief or faith in the Emperor as divine. This was compounded by the beginnings of the Imperial Truth, particularly those espoused by Euphrati Keeler, which only reinforced the Draconians' worship of the Emperor as descemded from the Kami and the son of the Sun Goddess. They participated in many battles, campaigning against the Warmaster's forces, clashing against enemy Knight Houses such as House Malinax in Beta-Garmon and even on Holy Terra itself. They also reinforced Tallarn against the Iron Warriors, fought against the World Eaters, Word Bearers and their allied Traitor Knight Houses and Titan Legions during the Shadow Crusade and the retaliatory Crusade of Iron to take back the worlds of Ultramar. One of their more notable actions was when they helped Loyalist Iron Warriors, White Scars, Dark Angels and Loyalist Imperial Army forces defend Janus from the forces of the Warmaster, which included the Warhound Titans of Legio Audax, the Iron Warriors, the Thousand Sons and World Eaters. Hundreds of Knights were sent to hundreds of warzones, determined to exterminate the Traitors for turning their back on the Divine Emperor. Foremost of these wars was the Razing of Prospero, where a significant contingent of Knights from House Yato fought alongside the Thousand Sons when the Space Wolves, Adeptus Custodes and Sisters of Silence attacked. There, the Knights of House Yato clashed against the twisted forces of House Malinax, and it was there that they became the bitterest of foes. From then on, the Knights of House Yato swore vengeance upon the sinister scions of House Malinax and vowed to annihilate them - which they failed to do so, despite clashing against them in many theaters of war, from the realm of Ultramar to Beta-Garmon, Tallarn and Holy Terra.
Despite suffering major losses, the jubilant House Yato took part in the Scouring, leading House Takeda, House Uesugi and the other Knight Houses of Draconis III in a campaign that saw them drive traitor Knight Houses, including House Malinax, back to the Eye of Terror. Alongside the growing Skitarii legions of Draconis IV and the expanding Draconian Defender regiments, the Knight Houses of Draconis III spent the next millennia recovering, though they frequently fought off xenos raiders such as ork incursions. They participated in the war against the green hordes of the Beast, fighting off countless orks that threatened to invade their sector.
After their recovery, around the 34th Millennium, the Shogun Yato Yoshitsune launched the Draconian Crusade to conquer the entire Draconian Sector and bring them under Imperial control. Within a century, the Knight Houses of Draconis III, their subordinate Draconian Defender Astra Militarum regiments, and their Skitarii allies and Cybernetica Cohorts from the forge world Draconis IV, as well as the venerable Titans of Legio Draconis, successfully brought over two hundred worlds to heel. The number would remain in flux and some worlds slipped out of Imperial rule, only to be reconquered later, while other new worlds were discovered and brought to the fold, but by and large, House Yato maintained a Draconian rule over the sector. The forge world of Draconis IV had their own interests, of course, subjugating a chain of forge worlds under their rule, which would later form the Helios Forges, all of whom would follow the Draconian doctrine and specialize in plasma and laser weaponry, as well as the manufacture of Knight suits and Leman Russ Executioner tanks. Hundreds of smaller Knight Houses would be founded across the Draconis Sector, benefiting from the vital supplies of war materiel from the Helios Forges.
There was little that could threaten countless Knight lances, the cyborg warriors and resilient automata of the vaunted Legio Cybernetica, near limitless men and tanks of the indomitable Draconian Defenders and the mighty Titans of the Dark Dragons. Even a Tyranid incursion was swiftly destroyed, a splinter fleet of Hive Hydra and a significant bio-fleet of Hive Behemoth destroyed when they approached the sector. On the Eastern fringe, a T'au attempt to turn several worlds over to the Greater Good was quashed, the young, upstart xenos suffering the wrath of the ancient war machines of House Yato. Even their Stormsurge ballistic suits were no match for the Dominus Knights' immense firepower, the latter's volcano lances ripping through hi-tech ballistic suits with astonishing ease. Humbled, the T'au were sent back to the Damocles Gulf to link up with Commander Shadowsun and concentate their forces on Agrellan. Oddly enough, House Yato ended up allying with the Farsight Enclaves to ward off several ork Waaaghs! and an invasion from a significant splinter fleet from Hive Leviathan. Recognizing the honor of the Fire Caste and seeing similarities, the Shogun decided it was in the best interest of the Imperium to sign a truce with the T'au - a truce that was inspired by the actions of the legendary Hero of the Imperium, Commisssar Ciaphas Cain. In secret, both forces sought to make use of each other, though in an honorable fashion.
Despite sending Knight lances to Cadia, they were unable to prevent Abaddon the Despoiler from smashing the bastion planet and were helpless to see the Great Rift tear the galaxy in half. For a while, the Draconis Sector was swallowed by warp storms, many of its systems cut off from each other. The Draconian Coalition was in ruins, with only the primary Draconis system itself remaining defiant in the face of daemonic incursions.
Fortunately, the warp storms eventually died down, replaced by the gleaming light of the Astronomican once more. With the Draconis system secured, the current Shogun, Yato Yoshimoto, declared a second Draconian Crusade, determined to take back the Draconis Sector and reforge the Draconis Coalition. The tech-priests of Draconis IV were only too happy to offer their help, for they too wish to reclaim their Helios Forges and once again reestablish that vital supply of war materiel and tireless industries. With reinforcements arriving from Terra, shortly after the newly awakened Primarch, Roboute Guilliman launched his Indomitus Crusade, Yato Yoshimoto is determined not to let the Lord Commander of the Imperium down. Should he succeed, the Draconian Coalition will be able to once more provide vital munition supplies, much-needed tanks and vehicles, armaments, important starships, Knight armors and Titans with their robust industries, manufactorums and forge temple-complexes.
However, it appears that some taint of darkness has been left behind on many of the worlds they are posed to retake...
On the tabletop, I have given my Knights of House Yato the custom Household Tradition comprising of two abilities: Glorified History and Slayers of Beasts. I picked these two because they represent my Knight House best. Before Engine War, I made use of House Griffith's Glory of the Charge or House Taranis's Omnissiah's Grace because I wasn't sure which one of these two was closest to House Yato - on one hand, they do like charging into combat. On the other, their close ties with the forge world of Draconis IV allows them to produce very resilient Knight suits. But Engine War came about and gave me the chance to create my own custom Household Tradition! So I wasted no time picking them, and Glorified History stood out to me among everything else.
As you all know by now, House Yato has a Glorified History, stemming back from the dark age of the Horus Heresy. We have fought over many battlefields and waged war in many campaigns, including the Liberation of Janus, the Shadow Crusade in the realm of Ultramar, the Battle for Tallarn, Titandeath in the Beta-Garmon system, the defense of Ryza and many other forge worlds, and even the Siege of Terra itself. I won't say we were practically everywhere, but my Knight House has certainly taken part in many battles during the Age of Darkness, fighting ferociously against the Warmaster's Traitors. Hence we have a storied history stretching back over ten millennia, proudly defending the Imperium even during those darkest days. Even now, in the 41st Millennium, House Yato and their subordinate Knight Houses of Draconis III remained one of the most powerful and numerous Knight Houses in the Imperium, with the forge world of Draconis IV maintaining incredible production, maintainence and repairs of Knight chassis and armored suits for the majestic House. In cruch, this is represented by their ability to r-roll a single hit roll every time they shoot, fight or fire overwatch (which costs command points now as a Stratagem...). Cool, I guess?
Additionally, as you saw above, the Knights of House Yato have fought against the many horrifying creatures indigeneous to Draconis III, including the Orochi, the gargantuan Yamata no Orochi and the leviathan Bake-kujira among many Ayakashi that inhabit the dense forests and bottomless seas of the verdant Knight World. The noble warrors of House Yato have thus become accustomed to hunting such massive beasts, which was why I chose the Slayers of Beasts for their second Household Tradtion ability, giving them a +1 to their hit rolls with non-Titanic Feet melee weapons against Vehicle or Monster units. Given that I don't really use Knights Gallant, this will benefit my other Knights (I'm looking at my Cerastus Knight Lancer, Cerastus Knight Atrapos, Knight Errant, Knight Preceptor, etc., as well as my Armiger Warglaives). It does nothing for my numerous Knights Crusader and Knight Castellan, though, but hey, they get to benefit from Glorified History, so whatever. Anyway, I'm happy to use custom Household Traditions to represent my personal Knight House, and Engine War has given me the tools to do so. When we get a new Imperial Knight codex, updated for ninth edition, I will return here and make the corresponding changes for my Household Tradition.
Oh, one last thing. House Yato's Allegiance Oath is to the Imperium, so they get the Questor Imperialis: Vow of Honor that gives them +1 to their Advance and Charge rolls. I am tempted to give them an Allegiance oath to the Adeptus Mechanicus, given how often they fight alongside the Skitarii and Cybernetica of Forge World Draconis IV, as well as their close ties with the Mechanicus gven them access to better technology and more resilient Knight suits, but I think Questor Imperialis suits them better in terms of lore and fluff. So Questor Imperialis it is. Heh. I mean, I picked Questor Imperialis for my Adeptus Titanicus House Yato Knight Household Army, so I'm going to stay consistent for my 40K army as well. Because...fluff. The narrative is what's more important to me.