Transferred to another world, but I'm saving the world of an Otome game!?

Chapter 6: The Vice Captain of the Knights and Me!?
Chapter 5: The king’s brother and Me?!?
Chapter 7: The Demon King, Vice Captain of the Knights, and Me?!
Chapter 5: The king’s brother and Me?!?
Chapter 7: The Demon King, Vice Captain of the Knights, and Me?!
A two-part one-shot about a guy accidentally transported to an Otome game by his sister. To get out, he needs to clear a love route, but he tries his best to find another way.