Aimer - 残響散歌 (Zankyōsanka) / THE FIRST TAKE

This is a live performance - albeit in a very controlled environment.

From the About section:

A microphone and a white studio. And 1 rule. You've got 1 TAKE. Perform anything you like. Show us everything you've got for that 1 moment. THE FIRST TAKE

This song also happens to be the opening theme for the Japanese animated show Demon Slayer: Kimetsu no Yaiba. I watched an episode and got bored, but I absolutely fell in love with Aimer. I especially recommend her album Open a Door from 2023.