"......I can't sleep." Asakura Shinji was at his wit’s end. Night after night, sleep escaped him. Even lying in bed with his eyes shut was no good. Instead, he’d get sleepy during the day at school, always in a haze... One evening, on a whim, he ended up going out into the town when everyone was asleep―― “You shouldn’t be out at this hour! Go home and get some sleep!” Shinji unexpectedly bumped into his homeroom teacher, Hagino Umi. Concerned, Umi listened to Shinji’s insomnia problem. “You need to make the most of each day. Then, you should be able to sleep soundly.” Though he received this advice, Shinji didn’t know where to start. After all, he spent his days in a daze, only coming alive when the sun went down... "Hmm... well, Sensei would love to help you in that case.... but..." Umi wanted to help, but her position as a teacher couldn't exactly condone such nighttime strolling behavior. Shinji, understanding this, ventured out again another night, not expecting much. There, he encountered――Umi-sensei, in a different outfit, pretending to be someone else. “Umm… I-I’m Ogino Miu!” Thus began a string of special nights, just the teacher (?) and her student, spending precious time together, a soothing balm for his troubled heart――