真しん性せい

noun

inborn nature; true character

Refers to a person's innate disposition or the fundamental nature of something. Often used in formal or literary contexts.

• 彼かれの真しん性せいはとても優やさしい。

  His true nature is very kind.

noun which may take the genitive case particle 'no'

genuine; intrinsic; essential

Used as a no-adjective to describe something that is authentic, inherent, or not superficial. Common in medical or technical contexts (e.g., 真性糖尿病 'true diabetes').