Healer

Yoon Dansae is a "healer" whose addictive voice heals souls but also drives people mad.
Jang Sejin, who also loves to sing, grows resentful when his brother favors Dansae over him.
Jang Kiha, seeking a true healer, mistakenly kidnaps Sejin instead of Dansae.

Out of spite, Sejin betrays his friend, and both are turned into castratos, forced to sing for the elite.
As Sejin's mental health crumbles, he’s drawn to Cha Leesuk, a client who desires only Dansae’s voice.

But will he ever notice Sejin?

(Source: Tapas, edited)