The onee-san who moved in the apartment downstairs had a mysterious charm that drew me in.

She was the flashy opposite of the plain and unpopular me.
Who would have thought that a girl overflowing with such sex appeal would seduce me and take my virginity!
I have no idea what she likes in me but, since then, she comes and we have sex every day.

However, she seems to have some kind of secret and that darkness is catching me in little by little...

[Translated from the official website]