Toilets & 'More'

"No KARAZ" is a new book series I have started to publish that deals with the question of why reviewers disappear in funny ways.
This book is part of the "No KARAZ" series. "No KARAZ" contains various short stories on different topics.
The book contains a single story that is about a couple who have moved into a new apartment with a housemate, where the couple is involved in a situation with the housemate! How will the couple solve the problem with their housemate?