In BNA there are important characters that are both able to fly but physiologically have their wings on different parts of their body.
(NOTE: Spoilers marked below are from Episodes 7, 8 & 9)
Michiru (Tanuki) have her arms turn into arm wings but Nazuna (kitsune) gets to have her wings on her back and keep her arms
both have the same experimental beastman blood syrum and can both transform/change shape at will?
Is it because
Nazuna has been groomed to be the silver wolf religion's idol and having wings on her back make her look more angelic while Michiru's wings are more practical since she already knows how to transform/stretch her arms?
Is there a plot related explanation? Or is it just a design choice?