From Renta:

Kaito is a college student who is a total womanizer. He brings home a different girl every night, annoying his next-door neighbor Asami and making him bang on the wall to shut Kaito and his guests up.
One day, Kaito hears Asami talking dirty on the phone...and it turns him on so much he ends up touching himself!
What's worse, Asami comes by to tell Kaito he knows what he was doing...
A love story between a neighbor with a hot voice and a college student with a thing for voices.