Dexter, a boy-genius with a secret laboratory, constantly battles his sister Dee Dee, who always gains access despite his best efforts to keep her out, as well as his arch-rival and neighbor, Mandark.

Set in a German-speaking country in the seventies, brother and sister Tyltyl and Mytyl live with their parents, a dog and a cat. When their mother becomes seriously ill on Christmas Day, Tyltyl and Mytyl receive the visit of Berylune fairy. It entrusts them with the task of finding the “blue bird”, the bearer of happiness, making them able to heal the mother. With their dog Tyrol, cat Shanet, and a range of spirits, they set out on a journey to find the “blue bird” and maybe learn happiness along the way.

It is a family meddling dating reality program where siblings come together to help each other find romantic partners.

This "sibling romantic comedy" revolves around Masamune Izumi, a light novel author in high school. Masamune's little sister is Sagiri, a shut-in girl who hasn't left her room for an entire year. She even forces her brother to make and bring her meals when she stomps the floor. Masamune wants his sister to leave her room, because the two of them are each other's only family.

Masamune's novel illustrator, pen name "Eromanga," draws extremely perverted drawings, and is very reliable. Masamune had never met his illustrator, and figured he was just a disgusting, perverted otaku. However, the truth is revealed… that his "Eromanga-sensei" is his own younger sister! To add to the chaos that erupts between the siblings, a beautiful, female, best-selling shoujo manga creator becomes their rival!