Eri, the protagonist, has a daily habit of checking out erotic social media accounts before going to bed.
Her favorite anonymous poster is a guy going by the alias "Kei."
And it just so happens that there is a guy at her workplace who looks and sounds similar to "Kei."

One day, when she is comparing her colleague to the images of "Kei" online to see if she could spot any differences... he catches her.
However, the colleague nonchalantly passes by presenting no particular reaction.
Eri experiences a brief moment of relief before... "Kei" appears right in front of her----