She is enshrined on an active volcano and named after a flower that lasts a week. Both facts are doing the same work: Konohanasakuya-hime is the deity of things that are magnificent and short, and the tradition that placed her on Mount Fuji understood exactly what it was saying.
One night, and an accusation
Her father is Ōyamatsumi, a deity of mountains, and she marries Ninigi after he has rejected her elder sister. She conceives after a single night, and he says out loud what he is thinking: one night is not long enough, and the child cannot be his.
Her response is not a protest. She builds a birth chamber without a door, seals herself inside, sets it on fire, and declares that if the children are the offspring of an earthly deity they will not survive, and if they are the heavenly grandchild's they will come to no harm. She gives birth inside the burning hut to three sons — Hoderi, Hosuseri and Hoori — whose names all contain the element for fire and mark the stages of the blaze.
Three things about the episode are worth holding onto. She sets the ordeal herself; the husband is a bystander throughout; and the test is an ordeal by fire of the classic legal kind, the sort of proof recorded in the Nihon Shoki elsewhere as a real judicial procedure using boiling water. Japanese myth has very few trial scenes, and its most famous one is a woman prosecuting her own case.
The chronicles do not report a reconciliation. The story ends with the sons, one of whom becomes the ancestor of the imperial line, and she is not mentioned again.
Fuji, and how she got there
Nothing in the Kojiki or the Nihon Shoki connects her to Mount Fuji. The association is medieval, and it comes from the fire.
Fuji erupted repeatedly and destructively through the historical period, most catastrophically in 864 and most recently in 1707, when ash fell on Edo for two weeks. A shrine tradition developed to pacify it, and the deity settled on was the goddess who had walked out of a fire unharmed with three children — a being who could stand inside an eruption. Fujisan Hongū Sengen Taisha at Fujinomiya is the head shrine of a network of roughly thirteen hundred Sengen shrines, and it owns the summit of the mountain above the eighth station, a fact confirmed by a Japanese court in the twentieth century after a long dispute with the state.
The summit shrine is her inner sanctuary. Every one of the several hundred thousand people who climb Fuji in a season is, technically, walking onto shrine property.
Women were not allowed up
The mountain was closed to women until the Meiji period, on grounds of ritual pollution — a prohibition that applied to a great many sacred peaks in Japan and was formally lifted in 1872, when the new government abolished such restrictions as incompatible with modernisation. A handful of women climbed before that in defiance or disguise; Tatsu Takayama is recorded as having reached the summit in 1832, dressed as a man.
That a mountain sacred to a goddess excluded women is not the contradiction it looks like. Exclusion here tracked pollution rules around blood and childbirth, not the gender of the deity, and Fuji was far from the only such peak — parts of Mount Ōmine in Nara remain closed to women today.
The blossom, and what her name actually says
Her name is usually rendered as something like "the princess who makes the trees bloom", and the sakuya element has been connected to sakura, the cherry. The connection is a folk reading rather than a secure etymology, but it has been operative for centuries: she is the deity of cherry blossom, and shrines associated with her are planted accordingly.
What follows from it is the aesthetic proposition at the centre of Japanese blossom-viewing. Cherry blossom is prized for falling — the flower is admired most in the week it is lost, and the entire vocabulary of mono no aware, the pathos of transience, is built on that. Her mythology states the trade-off in one line, through the sister she displaced: choose the blossom and you get beauty and brevity; choose the rock and you get neither. The hanami crowds under the trees each April are enacting the choice Ninigi made.
Sakura is now one of the most-used girls' names in Japan and has spread well beyond it, which makes her one of very few figures in this tradition whose association is a living modern given name.
Sake, and the third thing she is asked for
There is one more office, and it comes straight from the birth story. The Nihon Shoki records that when the children were born she brewed sweet sake from rice from a heavenly paddy and offered it in celebration. On the strength of that, Sengen shrines and the sake brewers' trade have a long association, and she is petitioned as a deity of brewing alongside her better-known roles in safe childbirth and easy delivery.
The combination — volcano, blossom, childbirth, sake — looks arbitrary until you notice that all four are processes that are violent, transformative and time-limited.
Fuji in fiction, the goddess less so
Fuji is the most depicted object in Japanese art and the goddess who owns it is not. Hokusai's thirty-six views do not show her. She appears occasionally in anime and games as an elegant fire-resistant figure, and in Onmyōji-type rosters, but nothing like as often as the mountain does.
Where she surfaces most reliably is in the sakura motif that saturates Japanese popular culture — falling petals as shorthand for beauty, loss and endings, deployed in every anime graduation scene ever animated. That image is hers, even where the name is absent, and it is a wider cultural inheritance than most of the deities with better stories can claim.
Why does she build the hut without a door?
Because the proof requires that nobody can intervene. A sealed chamber removes any possibility that she was helped, that the children were substituted, or that the fire was managed — the ordeal is only evidence if it is unsurvivable by ordinary means. The detail also echoes the ordinary practice it dramatises: birth in early Japan took place in a separate structure, the ubuya, built apart from the house and often destroyed afterwards, because childbirth was ritually polluting and the pollution had to be kept out of the dwelling. Sealing and burning a birth hut is an intensification of something people actually did, which is why the scene would have read as extreme rather than as absurd.
Is Iwanaga-hime worshipped anywhere?
She is, though thinly, and the shrines that keep her are unusually pointed about it. She is enshrined at Kirishima Jingū in Kyushu, at Ōyamazumi and other mountain shrines, and at a handful of small sites where she is petitioned specifically for longevity and for endurance — the exact quality her rejection cost humanity. A few of these shrines lean into the story, presenting her as a deity for people who have been passed over, which is a rare instance of Japanese shrine practice engaging directly with the emotional content of a myth rather than its ritual function. The Japanese family tree shows both sisters as daughters of the mountain deity, and the tradition overview explains why aetiologies of this kind cluster around the descent narrative.