How to Avoid the Captivity Ending

One day, I woke up and found myself inside a character raising simulation game. The character I possessed was in the position of a caretaker, raising the game's protagonist, 'Marvel'! [If you reach a happy ending, you can acquire a clue about how to return to your original world.] The system said so too, so I tried to work hard, see the ending, and go home. First of all, what you need everywhere is money and power! I got a job in the Knights Order to earn money, but it just so happened that the young duke needed a fake lover? "Become my fake lover. I will reward you handsomely." "Still..." "Ten times your current salary. That's the salary you'll receive while pretending to be my love...