His agency C-JeS Entertainment revealed on June 2, “The ballad song sung by Kim Jaejoong featured on today’s episode is the main theme song of ‘Triangle,’ and it will be released on June 9 at noon. The suddenly revealed song has been met with explosive interest, and it is currently the most searched topic on many search engines. Kim Jaejoong has personally participated in writing the lyrics, thus making the OST even more anticipated.”
With the idol himself playing the role of Heo Young Dal, the song helps elevate the love story between him and Baek Jin Hee (Oh Jung Hee) even further. The track starts off with a calming melody, but has a strong and emotional ending.
The OST will drop on June 9 at noon, so stay tuned! Meanwhile, you can hear a preview of below. It plays in the background of the scene near the end.