Storyline:

Lee Yeon was once the mountain guardian spirit (nine-tailed fox). For many centuries, he has lived in human form, searching for the reincarnation of his lost first love and eradicating supernatural beings that threaten the mortal world. Meanwhile, Nam Ji-A works for a TVC station as a PD of documentaries. 

She seeks out stories on the supernatural. Her parents were involved in a mysterious car accident and disappeared. She remembers a man who saved her in that accident. Rang, Lee Yeon's half-human younger brother, harbors a deep-seated contempt for all people. He continuously harms human beings as a way of pestering his brother.

Lessons:

 Don't  even dare to take out your claws

Try to absorb the force of happiness near you at times.

If you get heartbroken, don't do something stupid like falling in love next time.

Humans die too early to properly have a friendship

Life is short, so try your best in life but know to let go when something’s too unbearable it extends to people's love.

Don't eat or drink anything from strangers in this dangerous world.

Kids must be disciplined

What's more pathetic is a grown man who whines

Normally, two people grab meals and tea together after a degree of physical contact.

When you want to threaten someone, you must be in a position of power

The bigger the debt the more we lose control and become puppets.

You need to be careful with what you pay attention to.

People aren’t the only ones with eyes and mouths 

Marriage for a man is like scoring your own goal.

A journalist always digs until one hits a dead end.

Don't jump into a fire when you know it's dangerous.

Love can get you killed.

The one who loves the other person more becomes the prey

Sometimes, there are people you should never make deals with.

There is no solution for those who won’t save themselves.

Everyone lives with a painful memory of their own.

Sometimes, love eventually dies and disappears.

People whose curiosity comes first when they see dead people aren’t qualified to be a cameraman.

Sinners only have better lives until they take their last breaths.

In every gain, there’s a loss

Once A slave, always a slave because you can't do anything without your masters' approval

Melodramatic ones never meet a pretty end.

People come and go in your life.

No one will come to save you. So, protect yourself.

Remember the next you are full, try to get back up on your own.

Humans offer food to other people when expressing their gratitude.

When the protagonist falls in love with his long-lost love their tragic story will be repeated.

The power of love, that’s the most effective treatment.

Poem:

When I look at you, like you.

I want to kiss you,

When I’m alone with you,

Like this, I want to hold you,

I love you

I love you very much,

I love you,

I love you more than myself.

A Letter: ( from Lee Yeon to Ji A)

To my beloved Ji A

Do you like your gift? I hope you do. How stunning would you be in this dress?

I wonder… who’d get to stand beside you. Whoever it is, I wish someone decent.

If only I could actually be that nonchalant, but truth be told, I already hate the guts of this future husband of yours. I liked you, I liked how you viewed the world. Despite being born with a terrible fate, you never easily lose hope.

Drinking coffee with you, watching you sleep, all the paths we walked together, and even the time I spent waiting for you, I loved them all.

Ji A, butterflies filled my stomach when I called your name that rolled quickly off my tongue. You’ll now have to walk those paths without me, but you’ll get used to it.

You’ll do well.

So, please… let me go now

You must.