Why are the physiological wing locations on the beastmen body inconsistent?

Question

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)

Why does

Michiru (Tanuki) have her arms turn into arm wings but Nazuna (kitsune) gets to have her wings on her back and keep her arms

when

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?

Answer 1

Michiru's transformations are largely instinctive and driven by her emotional state and force of will.

As you noted, Michiru had already been transforming her arms by force of will.
- Michiru extends her arms in at least two episodes
- Michiru "bulks" her arms up to throw crazy hard pitches

When she needed to fly, that was the instinctive part of her body to change.

It should be noted that she also changes her feet into bird feet, likely another instinctive change. Michiru can do more elaborate changes (including reverting to a human and becoming a chameleon) only through deliberate concentration.

Nazuna, meanwhile,

has had considerably more practice at transforming. She is really a fox, but makes herself look like a wolf beastman at will (her shift is near-instantaneous when she and Michiru are interrupted unexpectedly). She also does a convincing facsimile of the real Silver Wolf, including going down on all four legs and glowing. It's likely she could will herself into any shape.

Most importantly, Nazuna saw this as a way to build herself as an artist. Michiru's flying transformation would not fit with her desired persona of a "cute" wolf.