That song is only known to be sung by TABLO of EPIK HIGH, because Funny Family 2 didn't produce an OST collection, so the sound source of that song has not been made public yet. The name is unknown. I don't know if it will be included in EPIK HIGH's album ~ You can listen to their songs, all in the style of ending songs ~ ~ PS. I really like that song, too. T T has been looking for it for years without success = =