Yukinari Sasaki is an ordinary high school boy with gynophobia...and an allergic reaction to physical contact with girls. One day, he falls from his bathtub into a bath on an alien planet named "Siren," where 90% of the population is female. There, he meets the sweet Miharu, whom he can touch without developing a rash! When the pair returns to Earth, they are joined by a quirky assortment of friends and enemies who make every day filled with laughter, life lessons, and fan service!