Cerberus Jam

Cerberus Jam is a completed shounen manga written and illustrated by SHIOTA Haruto.

Plot
Seri, a somewhat directionally challenged girl, went to Umeda for a job interview. Finding herself completely lost, she stumbles across a slightly opened door and decides to try her luck. She takes the stairs behind the door, emerging on a peculiar street half an hour later. Unknown to Seri, she has just mistakenly entered a place far more dangerous than she could ever imagine.