The vanguard; the person or group that leads the way at the front (e.g., in battle, competition, or an initiative).
彼は危険な作業で先陣を切って入り、仲間を助けた。
He went in first for the dangerous task and helped his colleagues.
登山隊は先陣を交代しながら頂上を目指した。
The climbing team took turns leading the way as they aimed for the summit.
新しい技術分野では若手が先陣を切ることが多い。
In new technological fields, young people often take the lead.