Orin and Chen are sister. My theory:
When Meiling became the gatekeeper of the SDM, she didn't know that SOME of the people who came were actually guests. So, one day when Remilia called for the prismriver sisters, when they came Meiling attacked them without hestitation. Of course, when they said that they were guests, Meiling apologized to them and she let them in. But before that, Lyrica said something like "You are a really good fighter!", letting Meiling know that Lyrica had interest in her. And so, after the concert, Lyrica kept talking with Meiling, while her sisters left. They fell in love with each other, and so, that's how Orin and Chen were born (They asked Marisa to make some pregnancy magic for them. But Marisa's magic wasn't the best so both of the children were of different species).
Orin was born first, but due to her power to carry souls, that was dangerous for everyone (?), they couldn't keep her. They heard of a Satori that lived underground that had lots of pets, so they sent her there. When the second child was born, they felt happy because she was just a nekomata. But the little nekomata was naughty and liked to ran off. And a rainy day, she ran off while her parents were asleep. She ran into the forest and she got hit by a branch of a tree. She doesn't remember who her parents were, so she was left alone until she found Ran. After these events, Meiling and Lyrica ddecided to brake up. And they never told anyone else than Marisa about them.
It's sad, isn't it TT?
