In Kunitsu-Gami renders, Soh's nails are white and Yoshiro's are black. (Dark purple in artwork). Cursed Soh's are long and bright red.
 |
| White |
 |
| Black |
 |
| Red |
 |
| This might be an artistic choice |
In-game, Soh has clear nails and Yoshiro black.
In regards to their nails in renders:
White to Yoshiro's black. Yin and Yang. Feminine principle and Masculine principle within the individual. But masculine and feminine are almost one in the same, which is an esoteric secret. (I won't discuss that here but maybe sometime.)
To ramble a bit...
Yoshiro is active, she dances and meditates, emanating Soh. Soh then fights Seethe in her stead and to the observer, she becomes the passive one. But they're both her, and both roles are fulfilled by her. She requires protecting and is protected and is doing the protecting. Her action of dancing is both active and passive in different frames of reference. This is true for all opposites.
The villagers can't see Soh. So, to them does it look like she dances and Seethe just get obliterated? :3