|“||My five requests that so many humans in the past have failed to complete... How many of them can you fulfill?||„|
|~ Kaguya Houraisan|
Kaguya Houraisan was once a princess of the Lunarians, a race of people living on the Moon. She was exiled to Earth over a thousand years ago for the crime of using the forbidden Hourai Elixir to make herself immortal. Arriving on Earth one day, she was found by a bamboo cutter and dwelt among the humans she had once despised. Though the Lunarians looked upon humans with contempt, Kaguya came to love her new home. Tales of her unearthly beauty led men from all across the land to seek her hand in marriage, Fujiwara no Mokou's father being one of them, but none could successfully complete her trial of the Five Impossible Requests.
The first was to bring her the stone begging bowl of the Buddha from India. The second was to retrieve a jewelled branch from the island of Mount Hourai. The third was to seek the legendary robe of the fire-rat of China. The fourth was to retrieve a colored jewel from a dragon's neck. The final task was to find the legendary Cowry treasure of the swallows. These potent treasures were eventually revealed to already be in Kaguya's possession in the final stage of Imperishable Night.
After years of exile, powerful emissaries arrived from the Moon; Kaguya had been forgiven of her crime and it had been decided that she should return. Kaguya, however, had grown to love life on Earth and had no desire to return to the lunar capital permanently. Enlisting the help of her friend Eirin, Kaguya escaped from the emissaries and fled to Gensokyo. Taking refuge in an ancient manor called Eientei hidden deep within a secluded bamboo forest, the two Lunarians began a new exile. After several centuries of isolation, she was eventually reunited with Mokou, who had also used the Hourai Elixir to become immortal, and the two continued their feud, murdering each other on a nearly daily basis.
She now spends her days living in Eientei in a carefree manner, sometimes holding exhibitions of Lunarian treasures there for the rest of Gensokyo to admire. Her long isolation has made her lonely, and she enjoys telling stories to any guests she might receive.
During the events of Imperishable Night, Kaguya had been hidden in a secret pathway along with the true moon by Eirin to ensure any Lunarians sent to recover Reisen would not discover her. The heroines of Imperishable Night, however, did discover her, and challenged her to return the full moon to Gensokyo. After being defeated, Kaguya unleashed her powers of eternity in an all-out bid to break the spell of the imperishable night cast by the heroines. Finally she relented and the true moon was recovered.
Kaguya has dark brown eyes and very long black hair. She wears a pink shirt with many white bows, and a long, dark burgundy skirt decorated in yellow with bamboo and flower shapes. Her 5 Impossible Requests are seen floating around her, probably waiting for her order to engage in a Spell Card attack.
- Eirin Yagokoro (Fellow Exile, Loyal Attendant)
- Reisen Udongein Inaba (Fellow Exile, Pet)
- Tewi Inaba (Allied Earth rabbit)
- Fujiwara no Mokou (Bitter enemy)
- Kaguya, and the whole of Imperishable Night, is inspired by the Japanese legend of the Moon Princess, also known as the The Tale of the Bamboo Cutter, sometimes called the legend of "Kaguya-hime" (Princess Kaguya).
- Her first name "輝夜" Kaguya, means "shining night", "sparkling night", or "radiant night". "蓬莱山" Houraisan refers to "Mount Hourai". And indeed, to not only be able to find the location and survive the impossible perils of ascending Mount Hourai (a legendary place filled with powerful youkai, mountain men, and other supernatural beings of every kind), but to also be able to enjoy a beautiful evening there, likely with some traditional Moon Viewing, would be to experience a truly otherworldly beauty: a shining night on Mount Hourai.
- Contrast Kaguya's name with "咲夜 十六夜" Sakuya Izayoi, a character speculated to have unrevealed connections to the moon and to lunarians, whose name means "blossoming night" (Sakuya) and the "full moon on the sixteenth night of each lunar month" (Izayoi). They also both possess powers of time control.
- Mount Hourai is the name of a legendary mountain that floats above the sea. Its inhabitants were said to possess, among other treasures, the elixir of immortality. *It was also the destination of one of Kaguya-hime's impossible tasks.
- A silhouette of Kaguya occupies the front of Imperishable Night's jewel case.
- Also in Inaba of the Moon and Inaba of the Earth, she is depicted as a terrible cook, and as innocent and naive.
- Kaguya and Mokou fight to the death every chance they get. Their relationship has been characterized as a constant "Tom and Jerry" back and forth battle.
- However, in Inaba of the Moon and Inaba of the Earth, Kaguya and Mokou's relationship seems much more casual instead—though that might be due to the carefree attitude of the author...
- In more serious doujin works, Kaguya is often depicted as having been driven insane or mentally unhinged as a consequence of her long life and inability to die permanently. However, in official works, namely Perfect Memento in Strict Sense, Inaba of the Moon and Inaba of the Earth and Cage in Lunatic Runagate, she is described as having a more cheerful and pleasant, if somewhat ditzy, personality, who likes to tease Reisen just like all the cast of Eientei. These different characterizations may stem from a more literal interpretation of the title of Kaguya's theme music, "Lunatic Princess"; believing it to be descriptive of Kaguya herself rather than the music.
- Kaguya is also the name of a Japanese lunar-orbiting probe launched in September 2007 as part of Project SELENE to map the moon's surface. At the time of the launch, fanart depicting Kaguya being "sent back to the moon" aboard the satellite, usually against her will, was popular (one tribute video even superimposed her theme music over footage of the launch of the rocket). The same probe was later intentionally sent crashing into the moon, giving way to a new surge of fanart. (Example)
- It can be conjectured that Mokou and Kaguya's rivalry symbolizes for the cycle of the Sun and the Moon: Kaguya, the Lunar Princess, and Mokou, who uses as an in-game avatar a fire bird that strongly resembles a phoenix.
- Kaguya was planned to debut as a playable character in Hisoutensoku, but was scrapped from the lineup due to time constraints. ZUN stated in an interview that her moveset as initially designed would have been overpowered and unbalanced the game and there was not enough time to properly balance her strength against the other characters (ironically the same issue was encountered with Mokou, who was also intended to be playable in the game).
- One of the few characters that does not wear any type of headgear.