Tooru has just moved in with his relatives: a mother, grandmother, 3rd year grade schooler, 1st year high schooler (just like Tooru), and 2nd year college student...all girls! Unfortunately for Tooru, the welcoming feast they serve him has salmon roe in everything, and Tooru hates salmon roe. But he can't just come out and say that...so he takes a bite. He quickly sneaks away to the bathroom to rinse away the taste, only to discover that he's become invisible!
Tooru uses this power just like you'd expect any curious teenage boy constantly surrounded by girls would: to spy on them. Follow the numerous adventures of the invisible boy.