一いっ線せん級きゅう

noun which may take the genitive case particle 'no'

top-notch; first-rate; leading

Describes something of the highest quality or rank, often used for products, services, or people. Functions as a no-adjective modifying a noun.

• 彼かれは一いっ線せん級きゅうのエンジニアだ。