Here's a translation of a short interview with Cave's main programmer, IKD, in the current issue of Arcadia. Many thanks to my wife Sayaka for translating more exactly.
ARCADIA No. 058 translation page 6-7,
ARCADIA(A)
IKD(I)
A: There is huge changes/different style compared with past videogames, then what reasons/intents to doing like that "Ibara"?
I: Speaking of "Musihime-sama"'s original mode, this is little different taste compared with "regular" Cave taste. But we were thinking to create/make more new and different line-ups recently. About this game "Ibara", I wanted to use 100% idea and creativities from who is in charge of this game, from his result, "Ibara" was created and that's why this game was not related with Cave games in the past.
A: Can you tell me about Dr. Teresa Rose and 5 sisters?
I: They are the relationship between parent and children but they are not bloods. Also, characters(shadows) on page 6 from left to right, 5th born Madie, 3rd born Kasumi, 1st born Race, 2nd born Shasta, and 4th born Midie.
A: Is there any relationship between Dr. Teresa Rose and 2 heroines of this game in past?
I: Yes, there is. Two heroines, Dain and Bond are negotiators. That's the key of this reason.
Excellent news. He totally sidestepped around exactly who/where the influence is coming from, but Ibara's credits should tell a very interesting story.
Yeah he totally sidestepped the question. He basically just said "Well yes, it's a very different style from Mushihime. We are looking at crafting new styles and I am leaving the man in charge of this project responsible for its appearance which varies from our previous games."