真まっ先さきに

adverb

first of all; before anything else; at the very beginning

Emphasizes doing something ahead of others or before any other action; often implies eagerness or priority.

• 彼かれは真まっ先さきに手てを挙あげた。

  He raised his hand before anyone else.

• 火か事じが起おきたら、真まっ先さきに逃にげてください。

  If a fire breaks out, get out before anything else.