Sharing a love for late-night radio, Kurage Mizuo, a quirky and intriguing classmate, hides a surprising secret—she’s a postcard-writing enthusiast! Determined not to be outdone, Mimei Fukuramori challenges her with her own postcards. A rivalry among listeners blossoms into friendship, as these two compete and connect under the moonlight. A heartwarming late-night radio rom-com, ON AIR!