noun, noun which may take the genitive case particle 'no'
keratin; horny substance; corneum; cuticle; collagen
Refers to the tough protein material in skin, hair, nails, and horns. In cosmetic contexts, often relates to dead skin cells or calluses. The gloss 'collagen' is less common; primarily means keratin.
角質を柔らかくするクリームを使っています。
I use a cream that softens keratin.
かかとの角質が厚くなってきた。
The callus on my heel has gotten thick.