Summary:
“This place is actually set in a GAL Game world!” And not only was I, who was raised in a prosperous family and was outstanding in everything not the main character, but I was also instead this world’s villainous and antagonistic Eldest Young Master?! I had decided. I shall forge an alliance with the strawberry girl, and together we shall wage war upon the main character for the one true love! I don’t care for his main character’s aura or his Yasashii Strategy. I shall open up a grand path to becoming the main character! I refuse to be a side character in a dating sim!"

Note:
The original series was tagged as harem, but it has been confirmed by the author herself (over and over again) that it won't be harem. It's adviced to read the original series first before reading this to understand the characters and story better. The first half of the original series was quite heavy with shounen element (more male gazey), but it'll eventually smooth out as the story progress.