After a routine beating at the hands of Kirie, Yukinari falls into his bathtub and disappears. Afterwards, he meets Miharu and discovers Seiren–a world near Earth with a 90% female population and a craving for men.
Enticed by the thought of spicy curry bread, Miharu ventures outside to find Yukinari's school and buy some, instead of waiting for him to come back. Along the way, she discovers the shopping district–and bananas.
Inspired by her daily horoscope, Kazuharu's sister, Lisa, kidnaps Yukinari and tries to marry him after a chance encounter on the way to school.
Kirie's planned outing with Yukinari becomes a search for Miharu within the vast Fukuyama estate.
An amnesiac Koyomi arrives from Seiren; and after some recollection, she remembers her mission of finding Miharu and return her home.
Koyomi observes Miharu's time on Earth. Despite her decision to return to Seiren alone, Miharu joins her. After a brief Seiren stay, Maharu allows Miharu to return to Earth, along with Tomoka and Koyomi.
Koyomi is given the task of finding a husband for Maharu and struggles with her androphobia. Tomoka competitively takes on that same task.
Miharu consumes an unknown liquid in chemistry class, and inadvertently creates a swarm of Miharu clones. Local shop keepers are then left to defend themselves from the clones insatiable appetite.
Tomoka and Lisa fight over the human-form Ebi. Lisa is then reminded about her magically animate doll friend.
Yukinari and friends travel to a hot springs resort. There, they find a female spirit unable to leave Earth and work together to help her move on to the afterlife.
After the Fukuyama siblings buy out various hot spring resorts, a ping pong challenge between Kazuharu and Koyomi wages a bet involving Kirie.
In an attempt to get close to Miharu, Fukuyama buys the school swimming pool, remodels it into a resort, and sends every boy but himself and (accidentally) Yukinari, tumbling out through a hole in the floor. And with the inadvertant help of Lisa's magic, he switches bodies with Yukinari.
An invitation to a baseball game turns out to be a trap set by Fukuyama. Blackmailed by him, Kirie is forced to fight in his all-girl kickboxing tournament.
Yukinari and Miharu finally go out on a date, with Fukuyama (and Kirie) in hot pursuit.
A fellow classmate of Yukinari and the others, Mamoru, appears as a cleaning superhero wanting to keep the school clean, confronting everyone that tries to litter. Miharu introduces him to Lilica, Fukuyama's maid, so that he learns how to do a better job.
Tomoka goes out to continue with her mission on getting a man for Maharu, but ends up keeping an eye for Kirie after she finds her dealing with some problems.
Miharu, Kirie, and Koyomi acquire a part time job at a video game convention in order to fix the bathtub (after being broken by one of Miharu's sneezing fits). When the forth part-timer fails to arrive, Yukinari is drafted into dressing up like a girl and playing eye-candy for a day.
To bring an end to Tomoka's boredom, Fukuyama starts a "unique" game of Mah-Jong involving dares and questionable clothing.
Everyone plays a part in a movie about three thief rabbit girls and two detectives. Fukuyama and Yukinari play as the detectives, and Miharu, Kirie, and Koyomi play as the rabbit girls. Lisa plays as a daughter and Mamoru as her father.
The school festival starts, oddly, at the same time that the portal to Seiren opens once again, sending a bewildered Maharu to Earth.
After a discussion involving Miharu's Seiko, Koyomi believes that she has spotted her father in the background of a news report, and begins to desperately search for him.
Miharu goes gift shopping for everyone while chaos breaks loose at Yukinari's house.
Miharu is taken back to Seiren by Ms. Kanata; Yukina's orders. Yukinari and the others prepare to go for her rescue.
Yukinari, Kirie, Tomoka, Lisa, and Maharu fight their way through to save Miharu from Yukina. At the end of the series, Yukinari, Miharu, Maharu, Kirie, Tomoka, Lisa, Fukuyama, Koyomi and Yukina all return to Earth and live happily ever after together.