Happiness!

Kaede is a devoted high school student who lives with her adopted brother Rin. She holds a quiet confidence that one day, when Rin finally starts showing interest in sex, he will make the obvious choice and turn to his loving sister. But what Kaede wasn’t counting on was the lords of heaven and hell coming to Earth, wanting Rin to mate with their nubile daughters! Rin, like any teenager would, takes full advantage of his newly acquired harem; but how long can he keep up his carefree, boxed-lunches-on-the-rooftop lifestyle, as the horde of girls on his tail grows?

In a world where magic is a reality, the young Louise is at the bottomof her class. Dubbed "Zero" by her classmates at Tristein Academy (due to her zero success rate for magic), Louise (along with all first year students) was charged with summoning a familiar; and instead of a cute magical creature, the familiar arrived in the form of... Saito Hiraga, a normal Japanese boy who was abruptly teleported from his own world?! Can both Louise and Saito come to terms with their new and complicated "relationship" and (more importantly) help Saito find a way home?

While visiting his hometown, junior high school student Michishio Nagasumi's life was changed forever when he nearly drowned. Though he was saved by a mermaid named San, there’s a catch -- her family is part of a merfolk mafia, and they abide by a strict rule: If a mermaid is discovered by a man, either he or the mermaid must die. That is, unless the man marries into the family! Faced with such a decision, Nagasumi can only oblige their customs and become a "happy" newlywed. Now, with a new school year around the corner, Nagasumi must find a way to deal with his new bride, keep her true nature a secret, and most importantly, escape inevitable death at the hands of San's over-protective father’s gang!