Tougijou no Reijou Erina

Erina, an arrogant and prideful countess.
Despite her skills, which once earned her the title of knight commander—
She’s falsely accused of a crime, exiled from her homeland, and reduced to slavery.
The one who buys her is none other than her former subordinate.

Now a slave, Erina clings to the pride of her noble upbringing.
Until she repays the price paid for her, her days as a slave will continue.
To escape her bondage as quickly as possible, she decides to become a female gladiator, earning prize money by fighting in the arena.

What harsh fate awaits the former countess, Erina?!

[Translated from dlsite]