[Zetsuen_no_Myuu]

We don't know a whole lot about Seii, much less what her true objectives are. With Rogas' aid, Seii was able to defeat Narukana, thus protected Eigou's verse by countering Narukana's dangerous null mana. That act should seems strange though because Setsuna opposes Eigou and Seii is Setsuna's kin, yet Seii basically helped prevented Eigou's verse from being destroyed.

Iirc, Ryutoria was

Spoiler for ...:

created by Law Eternals, as an existence close to an Eternal. Basically, she's a super uber Spirit with an existence and power that nears an Eternal. And that's without even wielding a shinken. She was designated as the Black or Red (can't recall which) Guardian and was tasked to help Temuorin. But Tokimi, being the thorn in Temuorin's side, interfered and was able to defect Ryutoria to the Chaos Eternal side. It's during this time that Ryutoria fought along side Wisdom's previous owner. Some unknown time later, Ryutoria got captured and was sealed in the center of Phantasmagoria, to be used as the central gear in Temuorin's schemes.

When Tokimi looked into the future, she saw an existence that had the possibility to become an important Eternal. The existence of Oruphaliru was essential to counter Temuorin's goal, but mainly to help realize that future (and her future lover ^). And so, Tokimi interfered again and created Oruphaliru by using a fragment of Ryutoria.

Originally Posted by Von Himmel

Where did you get that information?

In post entry 08/13 at here. You can follow up on the project's updates there.