Sudden Girlfriend Appearance anime involve a sudden change in the main character's life where he suddenly gets confronted with an individual he's sexually attracted to, the two of them inevitably becoming a couple.
Top 18 Sudden Girlfriend Appearance Anime to watch
- 1. Bakemonogatari
- 2. Fuufu Ijou, Koibito Miman.
- 3. Cardcaptor Sakura
- 4. Kaichou wa Maid-sama!
- 5. Maken-Ki!
- 6. Toaru Majutsu no Index
- 7. Oreshura
- 8. Sekirei
- 9. Castle in the Sky
- 10. Mysterious Girlfriend X
- 11. Sousei no Onmyouji
- 12. Kanokon
- 13. To LOVE-Ru
- 14. Campione!
- 15. Hentai Ouji to Warawanai Neko.
- 16. Urusei Yatsura
- 17. Onegai☆Teacher
- 18. Rec
1. Bakemonogatari

Koyomi Araragi, a third-year high school student, manages to survive a vampire attack with the help of Meme Oshino, a strange man residing in an abandoned building. Though being saved from vampirism and now a human again, several side effects such as superhuman healing abilities and enhanced vision still remain. Regardless, Araragi tries to live the life of a normal student, with the help of his friend and the class president, Tsubasa Hanekawa.
When fellow classmate Hitagi Senjougahara falls down the stairs and is caught by Araragi, the boy realizes that the girl is unnaturally weightless. Despite Senjougahara's protests, Araragi insists he help her, deciding to enlist the aid of Oshino, the very man who had once helped him with his own predicament.
Through several tales involving demons and gods, Bakemonogatari follows Araragi as he attempts to help those who suffer from supernatural maladies.
Bakemonogatari is finished and has 15 Episodes. It is also Known as: 化物語, Ghostory
2. Fuufu Ijou, Koibito Miman.

Third-year high school student Jirou Yakuin hoped to partner with Shiori Sakurazaka of the same class in the mandatory "Couple Practical" course. In this practical, students must demonstrate that they have the necessary skillset to live with a partner of the opposite sex while presenting a certain level of harmony to the video surveillance that grades them.
Unfortunately, random chance put his slightly subdued self into the practical with the person polar opposite to him, the gyaru Akari Watanabe. Akari on the other hand hoped to be paired with her crush Minami Tenjin.
Their hopes are doubly dashed when they find out that Shiori and Minami are assigned together. Thus, they reluctantly decide to cooperate to reach the top ten, which would give them the right to exchange partners if both couples agree. To that end, Jirou steals Akari's first kiss without realizing what he'd done, while giving a hurried good-bye kiss...
More than a married couple, but not lovers. is finished and has 12 Episodes. It is also Known as: 夫婦以上、恋人未満。, More than a Couple, Less than Lovers.
3. Cardcaptor Sakura

Sakura Kinomoto is your garden-variety ten-year-old fourth grader, until one day, she stumbles upon a mysterious book containing a set of cards. Unfortunately, she has little time to divine what the cards mean because she accidentally stirs up a magical gust of wind and unintentionally scatters the cards all over the world. Suddenly awakened from the book, the Beast of the Seal, Keroberos , tells Sakura that she has released the mystical Clow Cards created by the sorcerer Clow Reed. The Cards are no ordinary playthings. Each of them possesses incredible powers, and because they like acting independently, Clow sealed all the Cards within a book. Now that the Cards are set free, they pose a grave danger upon the world, and it is up to Sakura to prevent the Cards from causing a catastrophe!
Appointing Sakura the title of "the Cardcaptor" and granting her the Sealed Key, Keroberos tasks her with finding and recapturing all the Cards. Alongside her best friend Tomoyo Daidouji, and with Kero-chan's guidance, Sakura must learn to balance her new secret duty with the everyday troubles of a young girl involving love, family, and school, all while she takes flight on her magical adventures as Sakura the Cardcaptor.
Cardcaptor Sakura is finished and has 70 Episodes. It is also Known as: カードキャプターさくら, CCS, Cardcaptors, Card Captor Sakura
4. Kaichou wa Maid-sama!

Being the first female student council president isn't easy, especially when your school just transitioned from an all boys high school to a co-ed one. Aptly nicknamed "Demon President" by the boys for her strict disciplinary style, Misaki Ayuzawa is not afraid to use her mastery of Aikido techniques to cast judgment onto the hordes of misbehaving boys and defend the girls at Seika High School.
Yet even the perfect Ayuzawa has an embarrassing secret—she works part-time as a maid at a maid café to help her struggling family pay the bills. She has managed to keep her job hidden from her fellow students and maintained her flawless image as a stellar student until one day, Takumi Usui, the most popular boy in school, walks into the maid café. He could destroy her reputation with her secret... or he could twist the student council president around his little finger and use her secret as an opportunity to get closer to her.
Maid Sama! is finished and has 26 Episodes. It is also Known as: 会長はメイド様!, Class President is a Maid!
5. Maken-Ki!

Based on the manga series by Hiromitsu Takeda, this romantic comedy is about Takeru Ohyama, a typical perverted teenage boy. His new school doesn't require entrance exams, and it just turned co-ed! Unfortunately, his dreams of a happy high school life are dashed when he finds out the school is much more than it seems. All of the students wield a special item—a Maken—to unleash their magical abilities in duels! Can Takeru find a Maken that works for him? Even while trying to fit in at a new school and dealing with all kinds of girl problems?
Maken-Ki! is finished and has 12 Episodes. It is also Known as: マケン姫っ!, Maken-Ki! Battling Venus
6. Toaru Majutsu no Index

Academy City, Japan, is at the forefront of science. Besides being 30 years ahead of the world technologically, more than three-fourths of this peculiar city's population consists of students developing their psychic abilities as espers in various institutions. Among these students is Touma Kamijou, a high school boy with the lowest psychic rank of zero, but with a mysterious power no scientist can understand: "Imagine Breaker," which allows him to negate other supernatural abilities.
This, however, doesn't affect Kamijou's life in the least as he plays his role as a regular teenager; that is, until he meets the strange Index Librorum Prohibitorum, a young girl who has memorized the entire forbidden grimoires, and now a dangerous organization is hunting Index down. With several magicians looking to harm the girl, Kamijou will defend his new companion at all costs as he discovers a strange new realm of the supernatural.
A Certain Magical Index is finished and has 24 Episodes. It is also Known as: とある魔術の禁書目録, Toaru Majutsu no Kinsho Mokuroku
7. Oreshura

It is often said that events of the past shape what you become in the future. For Eita Kidou, a studious, hard-working student aspiring to earn a scholarship so that he can become a doctor, this is an undeniable truth after being abandoned by his love-addled parents. This event left him jaded to the notion of romance, seeing it as only a distraction that gets in the way of studying.
Unfortunately for Eita, his efforts hit a snag when he receives a confession of love from Masuzu Natsukawa, a transfer student with platinum hair and blue eyes. Eita sees through the confession, causing Masuzu to admit that she only did so because having a boyfriend would stop people from asking her out daily. She finds love to be just as much of a hindrance as he does, so by pretending to date, they can stave off advances from everyone else.
Eita refuses on the grounds that his classmates will be jealous, but Masuzu blackmails him by revealing that she has his journal and will post it online for everyone to see if he betrays her. Thus begins Ore no Kanojo to Osananajimi ga Shuraba Sugiru, a story that follows Eita coping with his new "relationship" and the complications that arise from it.
Oreshura is finished and has 13 Episodes. It is also Known as: Ore no Kanojo to Osananajimi ga Shuraba Sugiru, 俺の彼女と幼なじみが修羅場すぎる, Ore no Kanojo to Osananajimi ga Shuraba Sugiru
8. Sekirei

Struggling yet brilliant teenager Minato Sahashi has failed his college entrance exams for the second time, resulting in him being regarded as worthless by those around him. However, the course of his seemingly bleak future is altered dramatically when a beautiful, supernatural woman falls from the sky and into his life. That woman, Musubi, is a unique being known as a "Sekirei," a humanoid extraterrestrial with extraordinary abilities. These aliens are known for kissing humans carrying the Ashikabi gene in order to awaken additional latent powers deep within.Recognizing the potential within the seemingly insignificant youth, Musubi kisses the bewildered Minato, initiating a bond between the two of them. This drags him into the high-stakes world of the Sekirei, where he and his new partner must compete against others in a battle for survival called the "Sekirei Plan." However, unbeknownst to the contestants, there is far more at risk that what the competition initially entailed.
Sekirei is finished and has 12 Episodes. It is also Known as: セキレイ, Wagtail
9. Castle in the Sky

Tenkuu no Shiro Laputa takes place in a world where humanity once built great flying cities. A catastrophe later destroyed all of these majestic creations, forcing the human race to once again live on the ground. Despite these setbacks, humanity still has a passion for flight and explores the skies with planes and airships. A young girl named Sheeta is on one such airship, having been abducted by the government agent Muska. When the ship is attacked by the air pirate Captain Dola, Sheeta takes the opportunity to escape.
Saved by the grace of luck and magic, Sheeta is found by a young boy named Pazu. The two later discover that Sheeta's amulet is the key to finding Laputa—a legendary castle that is said to be the greatest of the flying cities. Together these new friends head out to find the castle and unravel its mysteries before the greedy and evil people of the world do.
Castle in the Sky is a Movie. It is also Known as: Tenkuu no Shiro Laputa, 天空の城ラピュタ, Tenkuu no Shiro Rapyuta
10. Mysterious Girlfriend X

Every girl is a mystery when you're a 16-year-old boy, but Mikoto Urabe is in another league. She carries scissors hidden in her panties. She sleeps on her desk every day. She seems to have no friends whatsoever. But none of that can compare to what happens when Tsubaki Akira decides on a whim to taste a drop of her drool while Urabe sleeps.
From that moment onward, things between Urabe and Akira are never the same, and the mysterious girl slowly becomes Akira's mysterious girlfriend. Along with their friends Ueno Kouhei and Oka Ayuko, Akira and Urabe try and navigate the minefield of high school first romance and all the strange things that happen along the way.
Mysterious Girlfriend X is finished and has 13 Episodes. It is also Known as: Nazo no Kanojo X, 謎の彼女X, MGX
11. Sousei no Onmyouji

Grotesque monsters known as Impurities reside in Magano, a realm parallel to the present day. Exorcists purify these evil apparitions to protect the people. Rokuro Enmado is opposed to becoming an exorcist, even though he has the talent to be one, but an oracle gives him the title of "Twin Star Exorcist," the name bestowed upon married exorcists. Benio Adashino, the girl who receives the title along with Rokuro, is determined to exorcise all the Kegare, or Impurities, in the world. The two find themselves wrapped up in more and more battles together as the Twin Star Exorcists...
Twin Star Exorcists is finished and has 50 Episodes. It is also Known as: 双星の陰陽師, Sousei no Onmyouji
12. Kanokon

Kouta has girl troubles of the supernatural sort. For some reason, he keeps attracting the attention of animal spirits!
Having spent most of his life in the country, Kouta is understandably nervous when he moves in with his grandma to attend a high school in the big city. He hoped to make a good impression, but having Chizuru, a beautiful fox spirit, hanging off his arm didn't seem to be the sort of image he wanted to have. She's not alone in her love for Kouta, either. Nozomu, a wolf spirit, as well as other youkai have their sights set on the hapless country boy.
Kanokon: The Girl Who Cried Fox is finished and has 12 Episodes. It is also Known as: かのこん, Kanokon
13. To LOVE-Ru

Timid 16-year-old Rito Yuuki has yet to profess his love to Haruna Sairenji—a classmate and object of his infatuation since junior high. Sadly, his situation becomes even more challenging when one night, a mysterious, stark-naked girl crash-lands right on top of a bathing Rito.
To add to the confusion, Rito discovers that the girl, Lala Satalin Deviluke, is the crown princess of an alien empire and has run away from her home. Despite her position as the heiress to the most dominant power in the entire galaxy, Lala is surprisingly more than willing to marry the decidedly average Rito in order to avoid an unwanted political marriage.To LOVE-Ru depicts Rito's daily struggles with the bizarre chaos that begins upon the arrival of Lala. With an evergrowing legion of swooning beauties that continuously foil his attempted confessions to Haruna, To LOVE-Ru is a romantic comedy full of slapstick humor, sexy girls, and outlandishly lewd moments that defy the laws of physics.
To LOVE Ru is finished and has 26 Episodes. It is also Known as: To LOVEる -とらぶる-, To Love You, ToLoveRu, ToLoveRu Trouble, To-Rabu-Ru, ToRaBuRu
14. Campione!

Some people suddenly find religion, but for 16-year-old Kusanagi Godou, it's that REALLY old time religion that's found him! As the result of defeating the God of War in mortal combat, Godou's stuck with the unwanted position of Campione!, or God Slayer, whose duty is to fight Heretical Gods whenever they try to muscle in on the local turf. Not only is this likely to make Godou roadkill on the Highway to Heaven, it's also a job that comes with a lot of other problems. Like how to deal with the fact that his "enhanced status" is attracting a bevy of overly-worshippy female followers. After all, they're just there to aid him in his demi-godly duties, right? So why is it that their leader, the demonically manipulative sword-mistress Erica Blandelli, seems to have such a devilish interest in encouraging some VERY unorthodox activities? Get ready for immortal affairs, heavenly harems and lots of dueling deities taking pious in the face as the ultimate smash, bash and thrash of the Titans rocks both Heaven and Earth.
Campione! is finished and has 13 Episodes. It is also Known as: Campione!: Matsurowanu Kamigami to Kamigoroshi no Maou, カンピオーネ! ~まつろわぬ神々と神殺しの魔王~, Campione!: Matsurowanu Kamigami to Kamigoroshi no Maou
15. Hentai Ouji to Warawanai Neko.

Youto Yokodera wants to be seen in a way different from most men: as a pervert. However, his lewd actions are often misinterpreted as good intentions, and people cannot see his true nature. Upon hearing rumors of a cat statue that can banish an unwanted trait, he searches for it and prays for his façade to be removed. But each wish comes at a price: those unwelcomed traits are transferred to someone else who desires them!
After realizing that vocalizing his dirty thoughts is not the best thing, Youto decides to regain his lost traits by seeking out the person who received them. Unfortunately, he was not alone in praying to the cat statue, and now he must not only fix his life, but the lives of others as well.
The "Hentai" Prince and the Stony Cat. is finished and has 12 Episodes. It is also Known as: 変態王子と笑わない猫。, HenNeko
16. Urusei Yatsura

Earth faces a huge crisis. Aliens want to invade the planet. Humanity's only hope rests with Ataru Moroboshi, who was chosen to represent Earth in a one-on-one duel with the aliens' chosen warrior. There is only one problem with this plan. Ataru is a womanizing, stupid loser. How in the world can he hope to succeed?
Selected to fight for the aliens' right to take over Earth is Lum, their curvaceous, bikini-clad princess. Luckily for Ataru, the duel takes the form of a game of tag. All he has to do to win is grab Lum's horns. Not so luckily for him is the fact that she can fly and, being a normal human, he most definitely cannot. Just when it looks like Ataru is destined to fail, his girlfriend Shinobu makes him a promise: she will marry him if he can win.
The encouragement is enough to motivate Ataru to succeed. But just when it looks like Earth is saved, he faces another problem. Lum misinterprets something he said and thinks that they are now married! Urusei Yatsura follows the unlikely relationship between the lecherous Ataru, the beautiful alien Lum, and all of the strange people they meet along the way.
Urusei Yatsura is finished and has 195 Episodes. It is also Known as: うる星やつら, Lamu, Lum, Those Obnoxious Aliens
17. Onegai☆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.
Please Teacher! is finished and has 12 Episodes. It is also Known as: おねがい☆ティーチャー, Onegai Sensei
18. Rec

Fumihiko Matsumaru is an average salaryman with no girlfriend. He invited his colleague Miss Tanaka to a movie but was stood up. Right at the time he was about to toss tickets into a trash can, a cute girl appeared and asked him not to waste those two tickets. After movie and dinner, he escorted her home and found they live in the same neighborhood, yet unfortunately her apartment caught on fire hours later. Having nowhere else to stay, rookie seiyuu Aka Onda moved to Matsumaru's place, and the two had started a "more than friend but not yet lovers" relationship under the same roof while keeping this secret from their employers.
Rec is finished and has 9 Episodes. It is also Known as: レック, Rec