Hiiragi Kouichi-kun received his first love letter with the words, "I'll be waiting for you after school behind the school gym. Sakuragi Umeko." However, his excitement turned to confusion when Sakuragi revealed that she wanted to take him to the planet R'lyeh. Disillusioned by her eccentricity, Hiiragi returned home. Yet, Sakuragai didn't give up easily, and it turned out that she may have been telling the truth after all. As it turned out, Hiiragi wasn't an ordinary guy either.