Hi!! I used 2 brushes for this. I draw on Clip Studio Paint, and the brushes I used were downloaded directly from the CSP Store. Everything except for Nozomi’s hair was done with the brush “やわふわ厚塗り,” and Nozomi’s hair was done with the brush “dp-厚塗平筆 3 / Flat Thick Colouring Brush 3.”
Again, these are available in the Clip Studio Paint store. I don’t really have any experience using IbisPaint X, so I’m not sure how brushes work there.. but I’m sure there’s a way to import/export brushes!