Love Hina

Keitaro Urashima promised a girl when he was young that they would meet up again at Tokyo University in the future. Sadly, in the National Practice Exam, Keitaro ranked 27th from the bottom. Knowing his grandmother owned a hotel, Keitaro intended to stay there while continuing his studies for Tokyo U, only to find out the hotel had long been transformed into an all-girls dormitory. Through an odd twist of fate, Keitaro eventually became the manager of the dorm, beginning his life of living with 5 other girls.

TONIKAWA: Over The Moon For You

The story follows a protagonist whose name is written with the characters for "Hoshizora" ("Starry Sky" in Japanese), but whose name is pronounced as "Nasa". On the day of his high school entrance exams, Nasa encounters a beautiful girl named Tsukasa. For Nasa, it feels like destiny is finally calling out to him that he will have a girlfriend, but things take a turn for the worse when Nasa is hit by a car and unable to attend his entrance exams. After Tsukasa helps the injured Nasa, he confesses his feelings to her, and she agrees to go out with him, but only if Nasa agrees to marry her first. A year later Nasa aces the entrance exams, but he decides to work a part time job and live by himself instead of going to school. After Nasa turns 18, Tsukasa re-appears, and their happy, romantic, and mysterious married life together begins. (Source: Crunchyroll)

Please☆Teacher!

Kusanagi Kei, a high-school student living with his aunt and uncle, has an encounter with a female alien. This alien is revealed to be a new teacher at his school. Later, he is forced to marry this alien to preserve her secrets. From there, various romantically-inclined problems crop up repeatedly. (Source: Anime News Network)

Oh! My Goddess (TV)

Keiichi Morisato is looking forward to university life. But in reality, he has no luck in anything, and he has trouble with clubs, love, etc. The truth is that he has an unlucky star above his head. One day, Keiichi is stuck watching the dorm while his sempai are away, and has a mountain of chores to do to boot. But Keiichi is a good-natured person, and is set about doing his duties. As he is about to finish his final chore, he makes a phone call to his sempai. But the words that came through the receiver are, 'Goddess Help Line.' Shortly afterwards, a beautiful goddess named Belldandy appears in front of him from the mirror of his room.

Please☆Twins!

Maiku Kamishiro's past has always been somewhat of a mystery to him. The only clue he has to who is family might be is an old photograph showing two young children, a boy and a girl, playing in a small pool outside of a blue house. In an attempt to find his family, he moves to this blue house and begins working as a programmer. He's living a comfortable life until the day two very different girls show up at his door, both in possession of the same photograph, and both claiming to be his twin. With no way to prove who is a relative and who is a stranger, Maiku allows both girls to move in with him until they know for sure. (Source: Anime News Network)