Ah of course! Let's take a closer look at the Ametsukana's magnum opus, the most powerful weapon ever created, the heirloom of a powerful clan and personal treasure of Adagumo no Yaorochi:
Aloof Sword — Tasouken
Name: Tasouken
In Tasouken (蛇叢剣), the characters respectively mean "snake" (蛇 ta), "cluster/gathering" (叢 sou) and "sword" (剣 ken).
"Snake" (蛇) is almost certainly a reference to its original owner, who is based on the monstrous serpent Yamata no Orochi; as well as their current owner, Adagumo no Yaorochi, who belongs to a group of snake-like youkai named orochi.
The second character, "cluster/gathering" (叢), is likely used in reference to one of the sword's alternate names (or rather, false names, according to Yaorochi): "Ame-no-Murakumo-no-Tsurugi" (天叢雲剣), the “Heavenly Sword of Gathering Clouds”.
Backstory: Distant Past
The Tasouken was forged a long time ago by Yago Ametsukana, and was granted as an heirloom by the heavens to a powerful clan, which had control over several provinces of Ancient Japan.
Jealous and fearful of the clan leader's power, rival clans threw them a party and gave them unusually strong sake. Once they fell asleep drunk, they cut him up into pieces and stole the sword.
Throughout history, many a sword was created based on the Tasouken, and they all, Tasouken included, went by a number of names: Kusanagi-no-Tsurugi, Ame-no-Murakumo-no-Tsurugi, Tsumugari-no-Tachi, and so on.
One day, the original Tasouken fell into the ocean, allowing the clan leader's descendant Adagumo no Yaorochi to retrieve it. However, its long time spent under the sea had completely rusted it, and it was but a shadow of its former self.
Mythological & Historical Inspiration
The Tasouken is based on a sword so ancient, we can trace it through history all the way into mythology: The Kusanagi.
Depicted below: An artist's impression of the Kusanagi, not the real thing, as it remains unseen.
Origins in Mythology
Kusanagi's mythological origins lie with the god Susanoo-no-Mikoto.
He was banished from the celestial realm of Takamagahara for being a terrible guest by its ruler, Susanoo's sister the sun goddess Amaterasu. He then wandered the earthly realm, where he came across an old couple and their daughter weeping together.
He asked why they were so distressed and the old man explained that he and his wife used to have eight daughters, but now only the youngest, Kushinadahime, remained.
They explained that the other daughters were taken and eaten by the monstrous eight-headed, eight-tailed serpent Yamata no Orochi (八岐大蛇). In response, Susanoo offered to slay the beast for them in return for Kushinada's hand in marriage.
Susanoo instructed the old couple to brew a saké distilled many times over and to build a gate with eight holes in it, each leading to a saké dish. When Yamata no Orochi arrived, it drank from the dishes and felt drunk asleep, allowing Susanoo to slay it.
As Susanoo was cutting one of the serpent's tails, he found within it a sword, offering it up to Amaterasu as an apology, this was the Kusanagi. This story is, of course, very heavily referenced in the Tasouken's own story.
Additionally, the false names given to the Tasouken and its imitations in its official profile are also based on this tale:
In the Kojiki, it is said to be originally named “Tsumukari no Tachi” (都牟刈の大刀), later named "Kusanagi no Tachi" (草那芸の大刀)
In the Nihon Shoki, it is originally named "Ame-no-Murakumo-no-Tsurugi" (天叢雲剣), the “Heavenly Sword of Gathering Clouds”
In both, it is later instead called "Kusanagi no Tsurugi" (草薙剣), "Grass-cutting sword" when the hero Yamato Takeru uses it to cut down burning grass in order to save his own life
According to the legends, Amaterasu later grants the sword to her grandson, the god Ninigi-no-Mikoto, to take with him down to earth as its new ruler. Ninigi would later sire the ancestors to the imperial Japanese family.
Ninigi was also granted the mirror Yata no Kagami and the bead Yasakani no Magatama. Along with the sword, they form the three imperial regalia of Japan, symbols of the Emperor's authority over Japan as the divine descendants of Amaterasu.
From Legends to History: The Second Sword
According to the Kogo Shūi, the descendants of the god Ame-no-Mahitotsu-no-Kami, on whom Yago Ametsukana is based, forged another Kusanagi during the reign of the legendary Emperor Sujin.
It is said that this copy's divine might matched that of the original, and that it is kept alongside the Emperors at their palaces in order to protect them. The latter point we do have historical evidence for.
From Legends to History: Enshrinement at the Atsuta Shrine
The original Kusanagi would also appear once last time in the legends as the sword of the hero Yamato Takeru, gifted to him by his aunt, who worked as the saiō shrine maiden at the Ise Grand Shrine, where the sword was kept.
Most notably, Yamato Takeru used the sword to mow down the burning grass around him, which his enemies had lit in an attempt to kill him. This is perhaps where we get the Tasouken's association with mowing things down from.
Depicted below: Yamato Takeru using the Kusanagi to mow down burning grass.
Yamato Takeru would end up leaving the sword with his wife prior to his final expedition, on which he passed away. After this, she brought the sword not back to the Ise Grand Shrine, but established a new shrine where the sword would be enshrined: The Atsuta Shrine.
This reconciles the legends with history, as our earliest records of the Kusanagi is that of it being enshrined at the Atsuta Shrine.
Alleged Losses Throughout History: The Original Kusanagi
The original Kusanagi enshrined at the Atsuta Shrine, according to its official statements, remains safely at the shrine until this very day.
Below: The Atsuta Shrine's prayer hall.
However, the shrine's records also note that the entire shrine had burnt down once, gotten captured by rivalling factions multiple times and that there had been an attempt at stealing the sword.
The last time the sword was officially seen was when the shrine was entirely renovated during the Edo period, under the rule of shōgun Tokugawa Tsunayoshi (1646-1709), by the priests who took a look at it when renovating the box it was kept in.
In the Meiji era, an imperial messenger was sent to investigate the status of the Kusanagi at the Atsuta Shrine. However, the Chancellor of the Realm at the time, Sanjō Sanetomi, put in an order to cease the investigation right as the box was to be opened.
All these events combine to make the shrine's claims that the very Kusanagi from the legends sit unchanged in the shrine very dubious. However, due to its sacred status, it is never displayed, and the truth remains obscured.
Alleged Losses Throughout History: The Second Kusanagi
The second Kusanagi is said to also have been lost, with tales ranging from theft to forgery to loss at sea explaining how this copy of Kusanagi was lost.
Historians now believe that there were likely multiple swords held to be this second Kusanagi, and is why it is said to have been lost so many times in so many ways.
This, combined with the dubious status of the Kusanagi at the Atsuta Shrine, makes many people believe that the real Kusanagi and its legendarily equal replica had already been long lost, its true whereabouts lost to time.
Most famously, and relevant to us, it is said to have sunk into the sea during the historical Battle of Dan-no-ura (1185), found between the Taira and Minamoto clans over control of the Emperor.
In the battle, the Taira were cornered by the Minamoto, upon which the Taira attempted to throw the imperial regalia into the sea to prevent them from falling into enemy hands.
This event is the very one referenced in the Tasouken's retrieval by Yaorochi. Now that the Tasouken's history is recounted, we can finally take a look at the future Len'en had painted for it.
The Earthen Miraculous Sword
Now in Mugenri, Yaorochi came across a replica of the Tasouken made of clay. To revive the sword, they tricked Sukune Katano, the replica's creator, into giving them the replica, and into helping them transfer the Tasouken's soul into the replica.
They had Sukune build a giant ritual chamber, which served as a vessel to ensure that the sword's power would not escape during its transferral into the replica.
Depicted below: The haniwa-shaped ritual chamber in the Unlost Woods, where the transferral ritual took place.
Once preparations were complete, Yaorochi ordered Sukune to stand guard outside and began.
Thrusting both the Tasouken and its clay replica into the ground, Yaorochi began transferring its soul into the replica, upon which the rusted Tasouken immediately crumbled into dust.
The ritual went on for several days, and when it was finally complete, Yaorochi simply drew out the clay sword and lightly tapped the ground with its blade.
The clay crumbled away to reveal the steel of the sword within, the Tasouken has returned. Filled with glee, Yaorochi headed towards the roof to await their "guests".
During the fight, the Tasouken's spirit, perhaps enhanced by the superb vessel Sukune had created, awakened, if only briefly. However, it soon subsided and has not been heard from since.
This was perhaps thanks to a magical inscription inscribed onto it by Adagumo no Saragimaru, designed to suppress its power and prevent it from performing its regular function.
Tasouken Mysteries
So that covers the Tasouken's history, both as a legendary artefact from our reality and its true story as told in Len'en. However, there are still many more mysteries related to it, here I'll mention a few:
Embodiment of the Armchair Theory
In BPoHC, Yago explains that the Tasouken is "incomplete", as the sword's true power cannot be properly wielded by anyone, not human, youkai nor god.
What Saragimaru Knows
Despite being impossible to be properly wielded, even according to its own creator, Saragimaru claims to know how to use it. However, this was never elaborated upon.
Additionally, it's unknown what "regular function" Saragimaru sealed away, although I personally believe it's related to its ability to "sever relations", as Yaorochi seems to be doing quite well with Sukune now.
Curiously, Suzumi Kuzu seems to be searching for information on how to use the Tasouken as well, although to no avail.
And that concludes this post on the Tasouken!
I hope I didn't go too far with the history and mythology, but I think this really highlights how the Adagumo's and the Tasouken's story gets muddled and confused with and throughout history.
Especially in the Tasouken's case, you can really see the impact it had by tracing its mythology and history in both our reality and in Len'en.
Like how Len'en reframes the various names and potential replicas of the Kusanagi as derivatives attempting to reach the original's splendour, when all who knew the original had been lost to time. (Consider revisiting the Tasouken's official profile sometime it's really good)
Anywho, that's enough rambling, this is long enough as is. As usual, I hope you enjoyed~ :)
[ID: An uncolored digital drawing of Adagumo no Yaorochi from the Len'en Project series. Yaorochi is drawn with simple chibi-like proportions, having a large protruding cheek and lacking arms. They hold the legendary sword Tasouken with one of their tails and look at it with large, oval eyes and tiny black pupils. There is a speech bubble coming from the Tasouken that reads, “It's me Orochi I'm the Tasouken speaking to you inside your brain. Listen to me Orochi. Leave your siblings, you don't need them”. /end ID]
Up ahead of the river, there the Withered Grove quietly thrives. The dark region was heavily clustered with trees, save for a clear area inside where the Harujion stood. A rare sight in this mystifying land, however, it continued to droop ever since then, wilting as energy left its form to provid...
A fairly short Len’en shipping fanfic, Harujion x Tasouken.
Tasouken: Now listen to me Yaorochi, I am talking directly into your ear now. I need you to do me a favor. You will do this for me. I need you to go to Gamestop, and I need you to ask the bastard working the counter if they have Bambi on the ps2. If you come back empty handed you’ll be in big trouble Orochi. You will never see the light of day.
