[Nerroth]

One of the guys on BL just posted this:

Okay, lots of stuff popped up on Seasons of Change, it seems. Confirmed for "not a sequel", Nasu says to think of it more like a Sakura route for Extra. The three playable Servants from the last game (Saber, Archer, Caster) are the ones that you'll be using again in this one. They'll all have new costumes, though only Saber's is finalized and the other two are still in the design stages. You can choose whether you want to use the new costumes or the old ones, too. Tail Girl is one of the enemy Servants that appears. She's very clearly an antagonist, and if you had to compare her personality to another Type-Moon character it'd be Luvia.