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Yukinari Sasaki (佐々木 雪成, Sasaki Yukinari)
Voiced by: Mamiko Noto, Daisuke Sakaguchi (Drama CDs) (Japanese); Yuri Lowenthal (English)
Yukinari has been ridiculed by girls all his life, and has developed an extreme case of gynophobia in which he suffers an allergic reaction whenever he comes into contact with one. One day, after he is kicked into his bathtub by Kirie Kojima, his next door neighbor, he is transported to the alien world of Seiren, a planet where men comprise less than 10% of the population. He meets Miharu who does not trigger his allergy. She follows him back to Earth and is the main cause of his misadventures involving girls and subsequent abuse by Kirie.
Miharu Sena Kanaka (ミハル·セナ·カナカ)
Voiced by: Ayako Kawasumi, Kawasumi (Drama CDs) (Japanese); Michelle Ruff (English)
Miharu is a resident of Seiren who pulls Yukinari Sasaki to Seiren and follows him back to Earth to live with him. She has a mark on her forehead shaped like three dots in a triangle called Seikon, which provides her with several powers, including the ability to travel between Seiren and Earth and the power to create explosions whenever she is in emotional distress. She is also the only woman who can touch Yukinari without triggering his allergy. Miharu has a large appetite and a rapid metabolism. On Earth, much of her focus is in questioning her friends as to whether something is edible or not (like butterflies), and her continuous misunderstandings about Earth (such as believing that April Fools' Day means that everyone on Earth lies for one day) are the title's primary source of humor. Despite this, she has a heart of gold, an explorer's fascination with Earth, and has a close relationship with Yukinari. She is an extremely innocent girl who does not show any discomfort with being partially or fully naked in front of Yukinari, and she does not lose her temper even when made the target of Fukuyama's lecherous actions, unless the process involves food or disrupts her eating time.
Kirie Kojima (小島 桐絵, Kojima Kirie)
Voiced by: Chiwa Saitō, Masumi Asano (Drama CDs) (Japanese); Lulu Chiang (English)
Kirie is Yukinari Sasaki's next door neighbor, classmate, and childhood friend who takes care of him from time to time since. She is especially well-endowed, which makes her a natural target for Kazuharu Fukuyama's perversions. However, due to her physical aptitude and martial-arts abilities, she always defeats him. She regularly beats up Yukinari Sasaki for his bad luck. Kirie inadvertently sends Yukinari to Seiren for the first time when she slugs him for innocently walking in on her when she was showering in his bathroom. Despite their often turbulent relationship, Kirie has a deep affection for Yukinari and usually tries to help him. Because of her strong character and appearance, Kirie attracts a large number of admirers among the boys in her high school, in particular Kazuharu Fukuyama who often molests and gropes her whenever he has the chance to. In the manga, Kirie is accosted by an alternate version of Lisa Fukuyama when she enters a parallel world through an enchanted mirror in Fukuyama's house. In the anime adaptation, she also attracts female admirers, specifically Kosame and Hijiri Kanata, much to her displeasure. A running gag throughout the series is Kirie's complete lack of cooking skills which result in the creation of food that is inedible and dangerous. Kirie has a fear of ghosts and the paranormal, and despite her tomboyish character enjoys collecting dolls.
Kazuharu Fukuyama (福山 和春, Fukuyama Kazuharu)
Voiced by: Ryōtarō Okiayu, Shin-ichiro Miki (Drama CDs) (Japanese); Liam O'Brien (English) of which O'Brien received a nomination for Best Actor in a Comedy at the American Anime Awards.
Fukuyama is a classmate of Yukinari Sasaki and Kirie Kojima. Fukuyama is a rich, powerful, corrupt, perverted, selfish, and arrogant boy, and while he often chases girls and insults Yukinari by calling him "Puny-Nari" (チビなり, Chibi-nari), he does show a serious, caring side in critical situations. He suffers androphobia to the point that he has developed an allergy that causes him to break out with a rash whenever he comes into contact with another male. He often appears without the others noticing until he announces his presence, whereupon he either gropes or strips the girls of their clothing, which always earns him a severe beating from Kirie. For unknown reasons despite sexually assaulting many girls including Kirie herself, he has never suffered consequences from the law. Despite his own lecherous behavior, Fukuyama is highly protective of his younger sister, Lisa, and strongly objects to her affections for Yukinari.
Lisa Fukuyama (福山 リサ, Fukuyama Risa; spelled as "Risa Fukuyama" in the Tokyopop manga translation)
Voiced by: Yuki Matsuoka, Satomi Kōrogi (Drama CDs) (Japanese); Hunter MacKenzie Austin (English)
Lisa is Kazuharu Fukuyama's slightly insane younger sister. Lisa is a master of black magic, which causes several issues throughout the series such as infesting her family's mansion with ghosts, summoning a giant octopus in the school swimming pool, and causing an explosion within a shopping center. Lisa is constantly accompanied by Hayate and Kosame, who cater to her every whim such as gathering intelligence or even kidnapping. She develops an infatuation for Yukinari after his appearance matches a description in her horoscope for her soul mate and often employs her magic to get closer to him—with predictably disastrous results. Although she considers Miharu a rival, she is very fond of Ebi, who reminds her of the pet cat she owned when she was a little girl. In the anime adaptation, Ebi's girl form reminds her of a doll she used to spend her days with, which she reunites with later on thanks to Tomoka's magic.
Koyomi Hare Nanaka (コヨミ·ハレ·ナナカ)
Voiced by: Masayo Kurata, Hekiru Shiina (Drama CDs) (Japanese); Carrie Savage (English)
Koyomi is an androphobic resident of Seiren. She has fear of men on Earth and her phobia is only made worse by being one of Kazuharu Fukuyama's favorite targets; in the manga, she keeps a diary of how many times he has accosted her. Originally sent to Earth on a mission from the Space Travel Agency to 'retrieve' Miharu Sena Kanaka, she later moves into Yukinari's house along with her companion Tomoka Lana Jude on a prolonged mission to find a husband for Miharu's sister Maharu. However, her fear of men makes the act of even talking to a man nearly impossible. Koyomi's favorite pastime is reading, but she has a natural talent for table tennis, having won a tournament for a similar sport on Seiren. In the anime adaptation, Koyomi is also searching for her father, a native of Earth, whom she eventually reunites with. Koyomi's mother possessed a Seikon mark, and Koyomi herself possesses a dormant form of Seikon allowing her to create a portal to Seiren after Miharu is kidnapped by Hijiri Kanata. After she loses in Fukuyama's Cosplay Mahjong game, she is forced to wear nothing but a python, which she later ironically adopts as a pet.
Tomoka Lana Jude (トモカ·ラナ·ジュード, Tomoka Rana Jūdo)
Voiced by: Ayaka Saitō (Japanese); J-Ray (English)
Tomoka is a resident of Seiren who is sent to aid Koyomi Hare Nanaka in finding Miharu's older sister Maharu a groom after her less than productive efforts. Although a child, Tomoka deeply resents being treated as one and insists that she is as mature as anyone else, despite frequent actions by her which prove otherwise. She gets along fairly well with Fukuyama, whom she later refers to as an older brother after the two team up to obtain some mutual objective. She has developed a small crush on him but it is not something he is aware of. Tomoka can also use transformation magic. In the anime adaptation, Tomoka frequently uses Ebi as a makeshift club for hitting almost anything and anyone; she becomes friends with Lisa after conceding defeat in a magical duel. She is also obsessed with Poyon, her favorite TV show character. Because she is a child, Tomoka is able to have contact with Yukinari without triggering his female allergy. She also looks up to Kirie as an older sister. For example, she follows Kirie's example of drop-kicking Fukuyama right in the face. Tomoka is later revealed to be a genius capable of instantly answering a complex math equation from a college entrance exam.
Ebi (えび)
Voiced by: Tomoko Kaneda (Japanese); Karen Thompson (English)
In the Mahjong episode, Voiced by Fumihiko Tachiki (Japanese); Dameon Clarke (English)
Ebi is a creature from Seiren that resembles a plump miniature seal with the face of a cat and a pair of large bobbing antenna, which causes Miharu to claim she resembles a shrimp (ebi is the Japanese word for shrimp). She is accidentally summoned by Miharu during a bath, and becomes a pet for Miharu and the girls. In the anime adaptation, Tomoka pulls her out of her bag. She suffers a great deal of torment at the hands of Tomoka, who uses her as a club, flail, fishing bait, or handball. When Tomoka transforms Ebi into a girl for a brief amount of time, Yukinari and Kirie pay more attention to the transformed Ebi than to her. In the anime episode where the gang play Mahjong, Ebi is able to think through the entire play in her mind but is unable to communicate the move to novice Tomoka, rendering her plan fruitless. Also in the anime, Ebi can shoot a powerful beam attack called the E-beam from her mouth although it takes a while to recharge.