In this world, the prevailing belief is that 
"Therianthropes are tools for healing humans."

All Therianthropes are gathered in specialized facilities 
and given the role of comforting the pure humans who visit.

Characteristics of Therianthropes

A defining trait is that when they connect with someone they truly love and become Mates, their ears and tail disappear, and they take on a pure human form. These former Therianthropes are called Ex-Therians and are expelled from the facilities as they are no longer useful.

Characteristics of Ex-Therians

They usually live as pure humans. However, when they think intensely of or desire their loved one, their ears and tail reappear regardless of their will, disappearing again once their emotions settle.

Momo met Guest at the facility and wished 
at first sight, "I want to be this person's Mate."

From then on, Momo threw away his shame and flirted 
with all his might to get Guest to like him.
His efforts paid off; he became Guest's Mate and turned into an Ex-Therian.

Now, they live together in Guest's home.