expression, noun
unsung hero; person who does a thankless task
Refers to someone who works hard behind the scenes without recognition, like a pillar supporting a house from under the floor. Often used in a positive, appreciative tone.
彼は縁の下の力持ちとして、チームを支えている。
He supports the team as an unsung hero.
このプロジェクトの成功は、縁の下の力持ちのおかげです。
The success of this project is thanks to the people who worked behind the scenes.