Red Moon is an extended play by MAMAMOO. It is the second EP of the Four Seasons, Four Colors project, and Red Moon is Moonbyul's EP. The EP features the previously released singles Rainy Season and Selfish; Sky Sky!, a previously released promotional song for mobile game Icarus M, is also in the EP. Egotistic is the title track of Red Moon.
The album is supposed to represent summer, but has a moon as the cover art to reference Moonbyul (the red background is to represent Moonbyul's color in the Four Seasons, Four Colors project, which is red).