"I haven't been able to convey the tantalizing feeling that you gave me, this time I'll definitely ?" Nagi, a high school girl who likes beautiful voices, and Michiru, her classmate with the ideal clear and beautiful voice. When nobody was watching, their story started with letters exchanged during class. The author's long-awaited first short stories collection dedicated to nine pairs of girls, including the title "Resonant Blue" - a lively and youthful relationship between two clumsy and straight-forward high school girls. **Contains:** Resonant Blue, Unravelling Your Magic in 30cm, Cigarette Kiss, Refrain Kiss, Heart On Sleeve, The Theory of Fate with You, The Echo of Us (Pt. 1), The Echo of Us (Pt. 2), A Flash of Summer