April's Naeun and Jinsol are the first up in the 'Four Seasons' project.
The 'Four Seasons' project is a project by composer Kim Hyung Suk and lyricist Kim Yi Na. The first part of the project is titled "Time Difference" and will be sung by April's Naeun and Jinsol. It's perhaps fitting that a group called 'April' will be singing the 'Spring' portion fo the 'Four Seasons' project.
The song will be released later today on March 1st at 6PM KST.