After escaping a bus hijacking with the help of masked superhero Strange Juice, Yuuta Iridatsu finds his soul separated from his body and in the care of a perverse cat spirit, Chiranosuke. As a spirit, Yuuta wanders around his residence, the Korai House, aiming to regain his body and observe the other residents: Meika Daihatsu, a genius inventor; Mikatan Narugino, a cheerful idol; Ito Hikiotani, a shut-in NEET; and Rabura Chichibu, a spiritual medium. After catching a glimpse of Narugino's undergarments, Chiranosuke reveals to Yuuta that he becomes exponentially stronger upon seeing panties. However, if he sees another pair while he is still a spirit, his power will cause an asteroid to crash into the earth, ending the world and killing his friends.

Punch Line follows Yuuta as he unravels the mysteries surrounding Korai House, its residents, and a villainous organization attempting to end the world. Will Yuuta be able to save everyone, or will the ever-present threat of panties result in their doom?