No clue who the character next to Kal'tsit is. Doesn't look like Projekt Red or Lappland or Rosmontis.
So, if I were to guess, it's probably that one Hololive fox.

Provence said:

No clue who the character next to Kal'tsit is. Doesn't look like Projekt Red or Lappland or Rosmontis.
So, if I were to guess, it's probably that one Hololive fox.

White hair and green eyes, I think that's Rosmontis though I can see why she doesn't look like Rosmontis

Could it be Neon? The daughter of Hellagur's friend he killed?

It can't be Rosman, the tail, hair, and height are completely wrong. If the tail was right then you could just argue she's older, but I don't think a catgirl is going to grow up to have a wolf tail. It can't be Neon, either, she has blue eyes and an eyepatch, apparently. It would also be extremely random for her to be here.

I checked every operator and looked through the entire set of currently available character CGs, no one fits this description. No one can agree who it's supposed to be on Twitter, either. Frustratingly, the artist has also refused to reveal who it's supposed to be, but did point out that the person reclined on the raised area is Lee.

Edit: What's extra weird to me, is that character was originally supposed to be Surtr according to a WIP teaser the artist posted. Why change it to a seemingly nonexistent character?

Tail and ears indicate it's probably a lupo, only lupos with white/grey hair and green eyes is Lappland and Projekt Red.

Hair length and demeanor doesn't line up with Lapp, so the closest has to be Projekt Red.

Red also has a story connection to Kal'tsit, so that also lines up too.

It seems like the artist just brightened the hair and eye color, which is why it doesn't line up with the in game art of Projekt Red

Pixiv post have Horn tag. Could it be her?

d0d0b1rd said:

Tail and ears indicate it's probably a lupo, only lupos with white/grey hair and green eyes is Lappland and Projekt Red.

Neither of them have green eyes. Lappland's are grey and Red's are yellow.

Belfegrad said:

Pixiv post have Horn tag. Could it be her?

That tag was added by another user, not the artist, so it doesn't mean anything. Doesn't really fit her either.

My guess is that the lighting's made the colors a little weird- I was thinking they could be pink like Cardigan, but that's obviously not right. Eyes are all wrong.

However, if you compare with Heidi's E2 art: the tail and eyes are the right shape and only a few shades off, which checks out with the lighting. My only reservation is the ears, but they seem pretty close, and obviously she does have a connection with Kal'tsit.

Think that's my closest guess, though. Haven't got anyone else with that tail and colors anywhere near close.

sylverfox said:

My guess is that the lighting's made the colors a little weird- I was thinking they could be pink like Cardigan, but that's obviously not right. Eyes are all wrong.

However, if you compare with Heidi's E2 art: the tail and eyes are the right shape and only a few shades off, which checks out with the lighting. My only reservation is the ears, but they seem pretty close, and obviously she does have a connection with Kal'tsit.

Think that's my closest guess, though. Haven't got anyone else with that tail and colors anywhere near close.

I'd like to guess she's Heidi too, but her hair and eye color don't match. Hmm...

OMGkillitwithfire said:

I'd like to guess she's Heidi too, but her hair and eye color don't match. Hmm...

She kinda looks like an aged up Sussuro to me.

Looks like Shirakami Fubuki to me, more than anyone else.