I love you too much, so please love me more as a younger sister than her.

I, Keita Majima, a normal high school student, was unexpectedly hired as part-timer at the game company of my dreams! My job was to be the "big brother for hire," here to help them create...... the ultimate sister character. It's the start of a comedy about a secret brother-sister contract! (Source: ComicWalker, translated)