I think this can belong here. Kubo's Klub Outside fanclub has this feature where members get to post questions and Kubo answers (some of) them. So far, I haven't seen that many of them translated, nor did I have the time to really look what's been translated so far.
Today, I've come across these two:
Q321:
When Byakuya fought Pepe, even though he was hit with the Love Kiss, he was not turned into a puppet. Is that because the mantle Byakuya was wearing was made from the Oken?
A321: That's correct. Come to mention, I couldn't find the right moment to mention this back then...
Q322:
When we are first introduced to the Soul King, he clearly has all four of his limbs. When did you actually decide to get rid of his limbs? Also, when Pernida Parnkgjas crushes the Second-Class Divine Soldier, they are shown to actually have a normal left hand too, so I'm thinking that back then it had not yet been decided that Pernida was going to be Soul King's Left Arm.
A322: Well, the setting I came up with for them is that "normally, they can hold an imperfect human form, but when they loose themselves they can no longer hold it together and their true identity (that of the left arm) is revealed", but since it's pretty hard to grasp I could've scrapped this idea. Anyway, I really wanted to draw the bit in which their hood tears apart when they into the Left Arm.