There's a story of it in Yuyuko's section in Perfect Memento.
Every year, someone died under that tree and it drank their blood, turning into a youkai with ability to lure peoples into their death (similar to Yuyuko). Yuyuko then sacrificed herself to seal that demonic property of the tree.
Yeah, according to her PCB profile, it was suicide. Yukari didn't actually have anything to do with sealing away the tree, though. (She helped with the Hakurei Border, but ...)
…So that her soul may rest in peace within Hakugyokurou, I will seal the cherry blossoms, and make it the barrier. My wish... is that she will never again reincarnate, and never again suffer pain..."
Sounds like implying the other way around. Saigyou Ayakashi is sealed and used to lock Yuyuko’s soul, so she will not reincarnate and suffer (from the karma she had for killing peoples).
Lick_King said: Ah, figures. Speaking of which, has there been an explanation regarding why Saigyouayakashi, being a cherry blossom tree, is named as an ayakashi?
The name Saigyou came from Saigyou Houshi, a legendary poet, monk and traveler. There are many traditions in various regions in Japan based on Saigyou, and many of them, in particular, are related to cherry blossoms. Thanks to his achievements, there are at least five places where the cherry trees have earned the name of "Saigyou's Cheery Trees".
There was once an old cherry tree in Saigyou's hermitage in Kyoto. Every spring, the cherry flowers blossomed beautifully and many people came to admire them. Saigyou disliked having so many people come and disturb the calm of his mind and spirit, and so that spring, he decided not to receive any more visitors. However, after they pleaded with him, he ended up allowing the visitors in reluctantly. He then recited a poem about the cherry trees' flaw in how it attracted so many groups of people to come and see the cherry blossoms. Then night fell, and an old man appeared in Saigyou's dream whilst he slept under the tree. The old man asked him about the meaning of his poem. "Cherry trees are plants that have no soul and hence do not have flaws in the same way that people do in this world," admonished the old man. As Saigyou listened to him, he realized that the old man must be the spirit of the cherry trees. The old spirit felt happy to have met Saigyou, and he danced, praising the cherry trees of various famous places around Kyoto, and then soon disappeared as the sun began to rise. When Saigyou awoke, he was surrounded by flower petals scattered around the whole ground like snow.
It is unusual for the cherry trees' spirit to be portrayed by an old man, rather than a beautiful woman. However, there is no doubt that this spirit is being depicted as a benevolent being.
Yukari's Profile from PCB: Yukari had known Yuyuko since before her death. She also knew that it was not Yuyuko who was sealed by the Saigyou Ayakashi...
... but that it was Yuyuko's body that was sealing the Saigyou Ayakashi.
I looked into the original too, there wasn't any mistake in translation. I think it was killing two birds with one stone. And I would like to point out that if Yuyuko died before than Saigyou Ayakashi is sealed, she wouldn't be revived.
