[Story] The berry became violet upon ripening

Since people can get spirited away to the past...
(The Beautiful World)

One day, Mary couldn't be found anywhere. She had disappeared and Renko felt devastated.

That day, Mary got trapped in her own dream world, spirited away thousands of years ago. So of course, she wouldn't return anytime soon...
This world wouldn't harm her anytime soon either, because it was her own world of illusions.
But, she realized... she couldn't come back to where she was from, at least, for now.
As Mary passed years alone in this dream world, she trained her own supernatural powers, to get out of this nightmare.
As her skills became more powerful, she was progressively leaving her humanity behind.
Forgetting bit by bit the memories of her past, her identity... and Renko.
Centuries passed.
Becoming a monster.
As countless clouds were rising, she was becoming violet; Yakumo Yukari.
Thousands of years passed.
For how long has she been in the world of illusions?
On occasions,
Something unfathomable would draw her towards humans and friendships.
Something unfathomable would make her go to the outside world.
You can't expect such an old creature to remember distant memories...

"...Although you were talking about dreams, how did the things from your dreams become reality?" (Renko in CoSD)
"She can create or destroy a place like Gensokyo whenever she desires." (PMiSS - Yukari's article)