JYJ3’s Note: Supernova is a South Korean boy band formed under Mnet Media. Its six members specialized in the areas of singing, dance, acting, rap and pop.
Vega Sungmo is the lead vocal. (Read more Link1, Link2)
[PARTIAL TRANS] Interview for TV Life Japan:
SungMo of Supernova:
Q: Which artist are you close to?
A: JYJ’s Jaejoong
Source: TV Life Japan
Translated by: @rubypurple_fan
Shared by: JYJ3
JYJ3 
no surprise tbh
Uhhhhhh, never even knew they’re close lol
[INFO] Jaejoong and Supernova’s SungMo composed “Baby I’m Sorry” together in Jaejoong’s home (May 17, 2012)
https://jyj3.wordpress.com/2012/05/17/info-jaejoong-and-supernovas-sungmo-composed-baby-im-sorry-together-in-jaejoongs-home/
When it was tweeted, the song wasn’t out yet. Maybe the title was changed, I cannot find the song in YT. I read that the group is more popular in Japan.
[INFO + SCAN] Supernova Talks About Jaejoong in Gokigenyou (Japanese TV show)
July 20, 2011
Supernova [Cho Shin Sung], a Korean boyband, appeared on Gokigenyou (Japanese TV show) and one of the members revealed that the advice he received from Jaejoong was “if progress step by step you ought to be able to reach the top, so work hard~” He was happy to receive such advice. And even though he is older, (Jaejoong) is a big senior.
our jaejoong is just loveable. period.
I heard supernova is popular in Japan but idk. Anyway, jaejoong is a social butterfly, I’m sure he knows a lot of people