In the world where I became the creator, only my favorite couple won't get together

Kakeru is an otaku high school student who loves Manga and fan creations. However, Kakeru cherishes Momo, his childhood friend who lives next door, like a younger sister, and he secretly wishes that she would end up with Aoi, a kendo boy in their class... He considers them the ultimate couple! Only the serious and innocent Aoi is someone he can entrust Momo to! Because it's so *moe*! One day, Kakeru obtains a mysterious pen and notebook that can change the genre of the world. Using this genre-changer, which is said to be an alien artifact, can he make his favorite couple get together...?