Pretender (feat. Choi Jun) sung by Uncle Young-woo

It is a lesser-known YouTube channel
featuring Kim Hae-jun (Choi Jun), Gu Jeong-mo, and Yoo Young-woo.
It is a Japanese-language channel (content involving music lives or Korea-Japan cultural exchange).
It seems like Japanese singers also perform there sometimes
(such as Kaho Takada, Ai Tomioka, etc.)
Even then, there were many comments saying the blonde guy sings well lol