I'm not referring to manga with animal spouses or shapeshifters or beasts as alphas. I read those manga too!
Rather I'm referring to entirely contemporary manga in contemporary settings with entirely non-magical elements and yet...
Quite abruptly, while reading, one of the characters will gain a wagging tail.
Like "golf" and "black coffee" the tail is an almost short-hand indicator of personality.
How extroverted and friendly and people-oriented is this guy or gal?
Just check out the tail!