初しょ期きメンバー

noun

founding member; initial member

Used especially for the original members of a music group, band, or project team.

• 彼かれはそのバンドの初しょ期きメンバーだ。

  He is a founding member of that band.

• 初しょ期きメンバーだけで最さい初しょのアルバムを作つくった。

  They made their first album with only the founding members.