An Introduction to the Lunar Emissaries: The Watatsuki Sisters

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The Lands Outside of Gensokyo

There are many current residents of Gensokyo who are not from there originally; there are some who come from the outside world, such as the Scarlet sisters, who hail from Europe, or Mamizou Futatsuiwa who emigrated from Sado, Japan. There are also those who come from worlds outside of the human realm of existence, such as Doremy Sweet from the Dream World, or Tenshi Hinanawi from Heaven. Even humans from the Outside World, seen from Sumireko Usami, have rarely found their way past Gensokyo’s border. As fantastical as the world of Gensokyo may seem, it only makes its irregular occurrences even more natural. And among all of these residents coming from all kinds of places, there are also those that come from the Moon.

Out of all of Gensokyo’s outsiders, the Lunarian pair of Kaguya Houraisan and Eirin Yagokoro may be the most unique. Those who are now known as Lunarians lived on the Earth thousands of years ago, but ascended to the Moon after Lord Tsukiyomi’s epiphany on the nature of probability, and became the first of their kind. Eirin Yagokoro, also known as the Brain of the Moon, is said to have taken part in the creation of the Lunar Capital, of which Kaguya Houraisan was one of the princesses. However, after the two conspired in creating the forbidden Hourai Elixir, an impure drug that bestows eternal life, Kaguya drank the elixir and was banished from the Lunar Capital back to Earth. Eirin always felt at fault for the princess’ exile, and loved her so; and when Kaguya’s punishment of exile was up, and emissaries from the Moon came to bring Kaguya back, Eirin returned with the other emissaries only to murder them, betraying the Moon and remaining on Earth with the princess.

While not initially taking refuge in Gensokyo, Eirin eventually created the mansion of Eientei for Kaguya and herself to live in and become their new home. Before taking in Reisen Udongein Inaba some 30 years before the events of Touhou 8: Imperishable Night, time stood still for Eientei, and it was hidden from history itself, as a safeguard to keep Kaguya from being discovered by the Lunar Capital. In Imperishable Night, Eirin cast an illusionary spell to hide the real Moon with a fake one, ensuring that Lunarians could not travel to Gensokyo to recapture Kaguya. But after the incident was resolved, the residents of Eientei realized that Lunarians would not enter Gensokyo in the first place, making their defenses pointless. And after seeing the cooperation between humans and youkai and generally becoming interested in the larger Gensokyo, Kaguya decided to open Eientei to the flow of time. While she was safe, Kaguya was dreadfully bored from living in eternal hiding and was glad to finally and truly live in Gensokyo.

But their supposed safety did not last; The story of Touhou Bougetsushou (comprised of the manga “Silent Sinner in Blue” (released from June 2007 to May 2009) and the short novel “Cage in Lunatic Runagate” (released on December 2009)), a tale which introduces two more Lunarian princesses, Watatsuki no Toyohime and Watatsuki no Yorihime, as they deal with hostility from both the Earth and Lunar Capital. As these characters have yet to appear in canon outside of these two stories, the following will cover the setup and beginning of the story to give some background for their inclusion into the overwhelmingly large world of Gensokyo.

Toyohime, the carefree older sister to the left and Yorihime, the serious younger sister to the right fit almost perfectly with Gensokyo's other sibling pairings...


A Land of Untainted Purity

The Lunar Capital is a city on the Moon filled with what the Lunarians see as “purity”, meaning that the land rejects the natural flow of life and death. As such, the Lunarians loathe the Earth in all its “impurity”, with life and death being everywhere all the time. To them, it is a truly horrifying place; so they have treated the Earth as the ultimate prison: a land where criminals are punished by being subjected to the cycle of life. This is the reason why Kaguya was initially punished with living on the Earth, and why the Lunarians look down on Eirin, who abandoned them in favor of staying with Kaguya on Earth. While most Lunarians share this mindset, there are two that go against these accusations, only to be suspected of treason in return. These two are the other princesses of the moon: Yorihime and Toyohime.

The Watatsukis were raised to be proper rulers of the Moon by none other than the Brain of the Moon herself, Eirin Yagokoro. For countless years before her departure, Eirin gave the sisters crucial teachings on how to harness their abilities, specifically assisting Yorihime in controlling her godly powers and helping Toyohime learn how to link sea and mountain. The two respect Eirin immensely as a teacher, referring to her as “Master Yagokoro”, but also feel kinship to her as distant relatives. She was their mentor for over a thousand years, always giving them advice, such as when the human Mizue no Uranoshimako somehow entered the Lunar Capital. It hurt them to see Eirin betray the Lunar Capital and never return, but as their teacher, they always loved her and could never hunt her down, even if that is what they are technically supposed to do as the Heads of the Lunar Defense Corps.

Their close link to Eirin, as well as their abilities, places them in great suspicion and distaste from the Lunarian populace. Toyohime’s ability especially, which allows her to link the seas of the Moon to the mountains of Earth, making her closely tied to the Earth, and by extension impurity. And at the time of Silent Sinner in Blue, there was evidence of someone calling upon the power of the Yaoyorozu no Kami (Eight Million Gods) to invade the Lunar Capital, which is exactly Yorihime’s ability, making her the prime suspect as a betrayer of the Capital, and further proving the Lunarians’ distaste for the sisters. The incredible strengths that were shaped by their mentor were now the seeds of distrust from their own subjects. Even when faced with such cruelty, Toyohime never appeared to care much, taking her usual trips to the Sea of Tranquility with peaches in hand. Yorihime was a lot more serious, insisting on harshly training her moon rabbit defenses daily to prove their innocence. Yet despite their differences, the two sisters agreed on one thing: to never give up on their teacher that they knew would never forget about them.

After Eirin left, the only people the sisters could truly confide in were themselves.


And forget about them she did not, as shortly after the events of the Eternal Night Incident, a shooting star was seen in Gensokyo, turning out to be another moon rabbit. Reimu Hakurei, unable to differentiate a rabbit from the Moon from a rabbit youkai, attempted to bring her to Eientei but was driven away. The next day the moon rabbit, hearing Eirin calling, left for Eientei herself. Eirin immediately recognized the species of the rabbit, realizing the shooting star was her, utilizing a lunar veil to escape from the Moon to Earth. This troubled her, as a potential way from the Moon to Earth only reminded her of the danger they avoided by hiding in Gensokyo in the first place. However, instead of killing the rabbit just like the emissaries from before, Eirin entrusted a letter to her and requested it be delivered to the Watatsuki sisters, knowing they are the only ones she could trust with her advice.

The delivery was problematic for the rabbit, as she left the Lunar Capital in the first place to escape from the tedious work of pounding mochi. However, she knew the great responsibility of the task she was given, so she risked her life and returned to the Lunar Capital and approached the palace. Toyohime welcomed the rabbit in (after an accidental fall on top of her), recognizing the lock-spell casted on the letter as Eirin’s work. And after explaining her story to the sisters, the rabbit was assigned to work with the other Lunarian Defense Corps and become their pet with the name Reisen (not to be confused with Reisen Udongein Inaba, who was the Watatsuki sisters’ previous pet). As for the letter, it was a warning from Eirin regarding the rumored invasion.

The gap youkai, Yukari Yakumo, once tried to invade the Moon with many youkai allies. This was known as the First Lunar War, although the title of war is a bit off. It was more of a massacre on the youkai end, as they were no match for the overwhelming power of the Lunar Capital. Perhaps it was because of the recent arrival of Eirin and Kaguya into Gensokyo, but Yukari desired revenge for the embarrassment from hundreds of years ago, supposedly caused by the Watatsuki sisters. She desired a Second Lunar War, but instead relying on sheer force, she would utilize her new allies. Yukari indirectly convinced the residents of the Scarlet Devil Mansion to build a rocket, which required the energy of a god to fly to the Moon. Fortunately for them, Reimu just finished training to harness the power of the gods after Yukari told her to train like a true shrine maiden. Coming with Reimu, Sakuya Izayoi, and Remilia Scarlet on the rocket was Marisa Kirisame, probably because she called shotgun. Many impure beings were prepared to set out for the Moon, entirely unaware of what awaited them…or even if they could truly make it.

Would the Watatsuki sisters truly be able to stop this rebellion, all while being looked down upon by the Lunarians? Eirin’s letter promised them success as long as they followed her plan. Not only did they finally have someone who they could trust, but it was the same person who prepared their abilities in the first place.

If it wasn't for Eirin, Reisen would have never been wrapped up in this second youkai conflict in the first place and meet her new owners...


Watatsuki no Yorihime: Capable of summoning divine spirits

A rather smug Yorihime, prepared to show off her powers to the unaware outsiders.


The human (and vampire) invaders somehow managed to crash land near one of the Moon’s seas, finding themself near some lunar peaches. Some moon rabbits were dispatched to keep guard, although they were overwhelmed immediately by the Gensokyo residents. Yorihime would not be taken down that easily, stabbing her blade into the ground only to trap the invaders with surrounding blades (similar to the focus shot Lord Gion’s Power). She was ready to eliminate them on the spot, but decided to follow Gensokyo’s spell card rules and defeat them one by one without bloodshed. Even if it was her first bullet battle, her sheer strength and incredible adaptability was enough to overwhelm each foe.

The thunder god Honoikazuchi served as her primary attacks against Sakuya (almost parallel to the spread shot, Lord Kashima’s Thunder Sword, although the power is derived from a different god). Combined with Kanayama-hiko no Mikoto’s power, Yorihime was able to return the knives onto the maid after her time stop and force her to surrender. As for Marisa, Yorihime showcased a combination of quick reflexes to avoid her Master Sparks and managed to reflect a Double Spark with Ishikori-dome no Mikoto to catch the magician off guard. Remilia did not fare any better, as she could not even hit Yorihime while she was possessed by Ame-no-Uzeme’s dancing and a swift sun attack from Amaterasu Oomikami was all it took to win.

Yorihime does summon these divine beings, but in order to take full advantage of this power, she must use her body as a medium for the god to take over. While the power she possesses may not be truly her own, it takes a very strong will and a deep focus to maintain a god within one’s body, which Yorihime has been training for countless years to master. As an aside, you may notice that the gods Yorihime used during SSiB differ heavily from the ones she uses during Lost Word. The gods of the Shinto are plentiful, made up of “Yaoyorozu no Kami,” or 8 million gods. There is a good reason for Yorihime to be so cocky about her power: it is effectively limitless against mortal enemies. And for once, perhaps she is glad to possess this strength rather than fear how it casts suspicion among the Lunarians.

Reimu is the only opponent that was capable of catching Yorihime off guard, all thanks to her own ability to summon Shinto gods. Instead of facing her head on, Reimu summoned the impure power of Oomagatsumi to curse the Lunar Capital, forcing the lunar princess to retaliate by purifying the bullets with Izunome. The duel eventually ended in a tie, as the two contenders ended up right next to each other with any further attacks endangering both of their lives. With that, Yorihime has single-handedly taken down the direct Earth invaders and even captured the rumored summoner of gods. But was she missing someone?

Watatsuki no Toyohime: Capable linking the sea and the mountain

Toyohime prepares to unleash her own otherworldly powers within Gensokyo.


Toyohime’s abilities are a perfect understanding of the teachings of Eirin Yagokoro herself. Thanks to the sage, she understood that any event with a probability of happening would end up occurring, a prime example being the Lunarians’ escape to the Moon in the first place. This is what caused Toyohime to learn her most notable ability: the power to link the sea and mountains, or the Moon’s seas and the Earth’s mountains (which is illustrated in her first spell, Promise: The Path Between Land and Sea).

That explanation might not make much sense, because they are not meant to. Toyohime is a true physicist that cannot be understood by the Earth’s current “theoretical” physics. This is what allows her to outwit even Yukari, who planned to sneak into the Lunar Capital during a full moon. Due to her previous invasion, she is aware of the Lunar Capital’s barrier weakening during a full moon, which should allow her easy access. Eirin predicted this move, however, and told Toyohime to use her ability to intervene with Yukari’s gaps and force her to make a wrong turn. After making Yukari return to the Bamboo Forest of the Lost, Toyohime confronts her with Reisen.

The lunar princess persuaded the youkai to surrender thanks to her futuristic powers and more futuristic technology. She states that her fan is actually a powerful Lunarian weapon capable of purifying the entire forest…on an atomic scale. She also wraps her and her shikigami, Ran Yakumo, in femto fiber, a rope that is actually made up of infinitely smaller ropes and can therefore never be cut through. Toyohime’s personality appears calm and upbeat despite the heavily complex abilities she possesses, which nearly parallels her previous master. While both sisters hold great love for Eirin, it is implied that Toyohime held a greater desire for her, shown by being the only one to hold the power to link land and sea.

As for Eirin, Toyohime brought Reisen along with her to deliver another letter to Eirin as a reply that her plan was executed flawlessly. They hoped to remain in touch with their mentor in the future and promised to hide her from the Lunarian authorities. As for the other invaders, Toyohime made sure to safely send back Marisa, Sakuya, and Reimila using her powers, but Reimu was left in the Lunar Capital. They required her to show off the ability to summon gods to finally lift Lunarian suspicion from the Wakatsukis. Reimu was fed well and stayed in the palace by the sisters, as they were still grateful for her help. After proving their loyalty to the Moon by preventing an invasion from Earth, they could finally take their place as Lunarian leaders.

…but did they truly stop every invader?

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About the Author(s)

I mainly go by Neku on Discord and primarily focus on writing articles for Touhou Lostword. You can usually find me on the Touhou Lostword Official Discord (Neku#9644) if needed for edits regarding any information on that side.