"Reverse Harem with the Target Sister and Her Brother Complex Admirers"

When my parents died and I was left alone with my young brother, I suddenly understood that this was the world of an otome game I had played in my previous life. In the game, I was a student teacher and was head over heels for the student council president, who was my brother's childhood friend. I was a minor character who harassed the protagonist. However, there's no way I would fall for the student council president in this life. Whether this is an otome game world or whatever else, as long as my brother can be happy. I must be the one to protect this child.