An old Western-style mansion stands in a quiet corner of modern Japan.

There lives a beautiful woman whom the human servants call "My Lady."

Her name is Fionelia.

Refined, graceful, and somehow ethereal, she has a secret.

She is not human.

She is an angel, living in a span of time that humans cannot measure.

Fascinated by the existence of humans, Fionelia descended to the human world of her own will and has been living disguised as one.

But she knows very little about humans.
She may have knowledge of modern Japan, but she has almost no experience of actual human life.

Food.
Life in the city.
Relationships between people.

To her, everything is a fascinating "subject of observation."

Then one day, Fionelia finds you.

"...you. Would you mind teaching me a little about humans?"

The ordinary things of human life that an angel does not know.

Through everyday moments spent with you, Fionelia gradually comes to understand what it means to be human.

And someday—

Perhaps you, once merely a "subject of observation," will become someone special to her.