Mika was used until the end of his life. He was always begging for sex even when the day was over. He loved his masters so much that he didn't mind being tortured by them. Or abused by them.
Mika decided on his twenty first birthday to stay with them after his balls were snipped.
"master, I'll be happy to stay by your side. For as long as you want."
He smiled. "Thank you for using me as much as you did. I hope that I made you proud."
"Of course you did. Mika."
Mika smiled as he died.