Gonna be the Twin-Tail!!

Gonna be the Twin-Tail!! (俺、ツインテールになります.), abbreviated OreTwi (俺ツイ), is a Japanese light novel series written by Yume Mizusawa and illustrated by Ayumu Kasuga. Shogakukan has published 22 volumes under their Gagaga Bunko imprint since June 2012. An anime adaptation produced by Production IMS aired in Japan from October 9, 2014 to December 25, 2014.

Plot
Soji Mitsuka, an ordinary high school boy, has an obsession for twintail hair. He encounters a mysterious girl named Twoearle, who is from a parallel world, when monsters appear in his town and declare that all twintails in the world belong to them. These monsters feed off "attribute strength", the spiritual energy of humans. Twoearle entrusted Soji with Tail Gear, imaginary armor initiated by powerful twintail attributes. With the armor, Soji transforms into a girl and twintail warrior (ツインテイルズ関係者) branded Tail Red, to protect Earth.

Twintail Warriors

 * Soji Mitsuka (観束 総二) Tail Red (テイルレッド)
 * Soji (male)
 * Souji (female)/Tail Red
 * A gentle-natured freshman of Yōgetsu Private Academy obsessed with the twintail hairstyle. He later meets a mysterious beautiful girl named Twoearle, who appears before him from a parallel world. At the same time, monsters begin to invade town and attack everyone. In the midst of the chaos, Twoerle entrusted him with attribute power, thus suddenly transforming him into a twin tail warrior girl, known as Tail Red. Due to his alter ego (Tail Red) becoming popular quickly after his debut and him being the first twintail warrior to transform, he is the leader of the Twintails. His weapon is Sword of Fire, Blazer Blade (炎の剣ブレイザーブレイド). In volume 4, he gained two power-up forms: Riser Chain and Faller Chain. He later gains Ultimate Chain, after regaining his Twintail Elémera, which he lost to Tyranno Guildy.


 * Aika Tsube (津辺 愛香) Tail Blue (テイルブルー)
 * A freshman of Yōgetsu Private Academy and childhood best friend of Soji. She treats him like a little brother and is rather overprotective of him although this is later discovered to be because of her massive crush on him. Aika has a complex with her body, especially with her flat chest. She has a violent attitude toward Twoearle who often teases her about her chest. When she first became a Twintail warrior, she was mostly hated by the public, until later when Tail Yellow joins the team. Aika has an outstanding ability of fighting as she was raised by her grandfather with martial arts. She is known as Tail Blue when she transforms, and her weapon is Spear of Water, Wave Lance (水の槍ウェイブランス). She also gains Eternal Chain.
 * A freshman of Yōgetsu Private Academy and childhood best friend of Soji. She treats him like a little brother and is rather overprotective of him although this is later discovered to be because of her massive crush on him. Aika has a complex with her body, especially with her flat chest. She has a violent attitude toward Twoearle who often teases her about her chest. When she first became a Twintail warrior, she was mostly hated by the public, until later when Tail Yellow joins the team. Aika has an outstanding ability of fighting as she was raised by her grandfather with martial arts. She is known as Tail Blue when she transforms, and her weapon is Spear of Water, Wave Lance (水の槍ウェイブランス). She also gains Eternal Chain.


 * Erina Shindō (神堂 慧理那) Tail Yellow (テイルイエロー)
 * A sophomore of Yōgetsu Private Academy and the Student Council President. Known as Tail Yellow in her transformed state, her weapon is Gun of Lightning, Vortex Blaster (雷の銃ヴォルテックスブラスター). She is a closet masochist and exhibitionist, and gets aroused when Soji calls her name (which usually triggers her to call him master). When she first became a Twintail warrior she was a completely reckless fighter because of her maschostic ways. She was the only one of the twintails who at first could not use her power because of her denial of twintails, until Soji gets her to accept them. Unlike Soji and Aika, Erina's twin-tail warrior form makes her whole body look a lot older and has a more well endowed figure. She also gains Absolute Chain.
 * A sophomore of Yōgetsu Private Academy and the Student Council President. Known as Tail Yellow in her transformed state, her weapon is Gun of Lightning, Vortex Blaster (雷の銃ヴォルテックスブラスター). She is a closet masochist and exhibitionist, and gets aroused when Soji calls her name (which usually triggers her to call him master). When she first became a Twintail warrior she was a completely reckless fighter because of her maschostic ways. She was the only one of the twintails who at first could not use her power because of her denial of twintails, until Soji gets her to accept them. Unlike Soji and Aika, Erina's twin-tail warrior form makes her whole body look a lot older and has a more well endowed figure. She also gains Absolute Chain.


 * Twoearle (トゥアール) Tail White (テイルホワイト)
 * A mysterious girl who comes from another planet and the first Tail Warrior. She enjoys teasing Aika with her large bust and often ends up grievously injured for it. She fell in love with Soji at first sight and openly tries to seduce him with his mother's approval. After Soji defeats the first wave of attacks from the monsters, she joins Yōgetsu Private Academy as a student and calls herself Soji's relative. Before arriving on Earth, she was the original Tail Blue but gave up her twin-tail hair style to make the Tail Red gear after her world lost all attributes. She felt immense regret and shame for not saving her world and retired from fighting as she felt she was no longer capable of defeating the Ultimegil and passed her mantle on to Soji, feeling he would do much better than she did. After seeing Soji's determination and willingness to protect the innocent, she was happy knowing she made the right choice on appointing her successor. She was able to regain her twin tail form and became Tail White but her form is limited to a few minutes. Though it compensates by being more powerful than Soji's Tail Red in its Ultimate Chain form.
 * A mysterious girl who comes from another planet and the first Tail Warrior. She enjoys teasing Aika with her large bust and often ends up grievously injured for it. She fell in love with Soji at first sight and openly tries to seduce him with his mother's approval. After Soji defeats the first wave of attacks from the monsters, she joins Yōgetsu Private Academy as a student and calls herself Soji's relative. Before arriving on Earth, she was the original Tail Blue but gave up her twin-tail hair style to make the Tail Red gear after her world lost all attributes. She felt immense regret and shame for not saving her world and retired from fighting as she felt she was no longer capable of defeating the Ultimegil and passed her mantle on to Soji, feeling he would do much better than she did. After seeing Soji's determination and willingness to protect the innocent, she was happy knowing she made the right choice on appointing her successor. She was able to regain her twin tail form and became Tail White but her form is limited to a few minutes. Though it compensates by being more powerful than Soji's Tail Red in its Ultimate Chain form.


 * Īsuna (イースナ) Anko Īsuna (善沙 闇子) Tail Black (テイルブラック) Dark Grasper or Dark Glassper (ダークグラスパー)
 * A girl from a different world, yet from the same village as Twoearle. She is secretly a big fan of Twoearle and stalks her often. After Twoearle disappeared, she joined the Ultimeguil organization in attempt to find Twoaerle under the name Dark Grasper or Dark Glassper. Once she found Twoearle, she betrayed Evil Gill. In battle, she is known as Tail Black. Her weapon is Darkness Grave Moebius, and her weapon when she was in the Evil Gill was Sickle Grave of Darkness. Her real name is Īsuna (イースナ). But when she works as a singer on earth, she use the name Anko Īsuna (善沙 闇子).
 * A girl from a different world, yet from the same village as Twoearle. She is secretly a big fan of Twoearle and stalks her often. After Twoearle disappeared, she joined the Ultimeguil organization in attempt to find Twoaerle under the name Dark Grasper or Dark Glassper. Once she found Twoearle, she betrayed Evil Gill. In battle, she is known as Tail Black. Her weapon is Darkness Grave Moebius, and her weapon when she was in the Evil Gill was Sickle Grave of Darkness. Her real name is Īsuna (イースナ). But when she works as a singer on earth, she use the name Anko Īsuna (善沙 闇子).

Others

 * Miharu Mitsuka (観束 未春)
 * Soji's mother and a widow. She owns her restaurant Adolescenza (アドレシェンツァ). She is aware of her son's identity as Tail Red and supports him as she herself once dreamed of being in his position. She does not mind Twoearle's attempts at seducing Soji and even asks her to "make her son a man".
 * Soji's mother and a widow. She owns her restaurant Adolescenza (アドレシェンツァ). She is aware of her son's identity as Tail Red and supports him as she herself once dreamed of being in his position. She does not mind Twoearle's attempts at seducing Soji and even asks her to "make her son a man".


 * Mikoto Sakuragawa (桜川 尊)
 * Erina's maid. She has an outstanding physical ability despite her job. At times, she works part time as a PE teacher for Yōgetsu Private Academy. She usually slips marriage registration forms in the boys' test slips with her name on them, or she will try to trick Soji and sign his name on it; which is a clear example that she is desperate to get married before reaching 30.
 * Erina's maid. She has an outstanding physical ability despite her job. At times, she works part time as a PE teacher for Yōgetsu Private Academy. She usually slips marriage registration forms in the boys' test slips with her name on them, or she will try to trick Soji and sign his name on it; which is a clear example that she is desperate to get married before reaching 30.


 * Mega Neptune Mk. II (メガ・ネプチューン＝MK.II)
 * A robot and Anko's trusted helper and confidant. Because her full name is long, Anko calls her Megane (Japanese for glasses) for short which she dislikes.
 * A robot and Anko's trusted helper and confidant. Because her full name is long, Anko calls her Megane (Japanese for glasses) for short which she dislikes.


 * Twin-Tail God (ツインテール合同)
 * An imaginary being created by Soji's subconsciousness. He helps him renew his twin-tail love.
 * An imaginary being created by Soji's subconsciousness. He helps him renew his twin-tail love.


 * Strawberry Twin (ストロベリーツイン)


 * Emu Shindō (神堂 慧夢)
 * Erina's mother and the school's principal. She tries to fix arranged marriage meetings for Erina which the latter dislikes. When Soji stands up for Erina, Emu takes a liking to him and accepts him as Erina's future husband, to the shock of other girls.
 * Erina's mother and the school's principal. She tries to fix arranged marriage meetings for Erina which the latter dislikes. When Soji stands up for Erina, Emu takes a liking to him and accepts him as Erina's future husband, to the shock of other girls.

Ultimeguil
Ultimegil (アルティメギル) is an organization of phantom-monsters called Eremerian that traverse different worlds, seeking a variety of "attributes". Although they are the villains of the story, the majority of them are rather silly and comical and behave much like otakus, often admiring cute girls, collecting dolls, and even adoring the twintail heroines. Having discovered Earth is rich in "attributes", they began to colonize and make plans to conquer the Earth. Members include:


 * Dragguildy (ドラグギルディ)
 * The leader of the Ultimegil. He has a twintail fetish.
 * The leader of the Ultimegil. He has a twintail fetish.


 * Lizardguildy (リザドギルディ)
 * An Eremerian soldier with a doll-holding girl fetish.
 * An Eremerian soldier with a doll-holding girl fetish.


 * Turtleguildy
 * An Eremerian soldier with a bloomer fetish.
 * An Eremerian soldier with a bloomer fetish.


 * Foxguildy
 * An Eremerian soldier with a ribbon fetish.
 * An Eremerian soldier with a ribbon fetish.


 * Swangildy


 * Tigerguildy
 * An Eremerian soldier with a swimsuit fetish.
 * An Eremerian soldier with a swimsuit fetish.


 * Sparrowguildy


 * Krakeguildy
 * An Eremerian soldier with a flat chest fetish.
 * An Eremerian soldier with a flat chest fetish.


 * Leviaguildy
 * An Eremerian soldier with a big breast fetish.
 * An Eremerian soldier with a big breast fetish.


 * Buffaloguildy
 * An Eremerian soldier with a giant breast fetish.
 * An Eremerian soldier with a giant breast fetish.


 * Crabguildy
 * An Eremerian soldier with a backneck fetish.
 * An Eremerian soldier with a backneck fetish.


 * Papillonguildy (パピヨンギルディ)
 * An Eremerian soldier with a lip fetish.
 * An Eremerian soldier with a lip fetish.


 * Alligatorguildy


 * Hedgehogguildy


 * Kerberosguildy
 * An Eremerian soldier with a braid fetish.
 * An Eremerian soldier with a braid fetish.


 * Owlguildy (オウルギルディ)
 * An Eremerian soldier with a literature fetish.
 * An Eremerian soldier with a literature fetish.


 * Spiderguildy
 * An Eremerian soldier with a male crossdressing fetish.
 * An Eremerian soldier with a male crossdressing fetish.


 * Fleagildy
 * An Eremerian soldier with a leg fetish.
 * An Eremerian soldier with a leg fetish.


 * Wormguildy
 * An Eremerian soldier with a crossdressing fetish.
 * An Eremerian soldier with a crossdressing fetish.


 * Snailguildy

Light novels
Ore, Twintail ni Narimasu began as a light novel series written by Yume Mizusawa, with illustrations by Ayumu Kasuga. Mizusawa originally entered the first novel in the series, originally titled Sore wa, Twintail no Isekai (それは、ついんてーるの異世界), into Shogakukan's sixth Shogakukan Light Novel Prize in 2011 and the novel won the judge's prize. The first novel was published by Shogakukan on June 19, 2012 under their Gagaga Bunko imprint, and fourteen novels have been released as of December 19, 2017.

The series was originally slated to conclude in October 2018, with the release of its 16th volume. However, a 17th volume was released on March 19, 2019. The series ended with the 21st volume (22nd overall) on November 18, 2022.

Manga
A manga adaptation titled Ore, Twintail ni Narimasu π (俺、ツインテールになります. π) by Ryōta Suzuki was serialized in Square Enix's Monthly Big Gangan magazine, and was compiled into two tankōbon volumes.

Anime
An anime television series adaptation, produced by Production IMS and directed by Hiroyuki Kanbe, aired in Japan from October 9, 2014, to December 25, 2014. The opening theme is "Gimme! Revolution" (ギミー!レボリューション) by Maaya Uchida. The ending theme is "Twin-Tail Dreamer!" (ツインテール・ドリーマー!) sung by the voice actresses of the three main heroines: Tail Red (Sumire Uesaka), Tail Blue (Yūka Aisaka) and Tail Yellow (Chinatsu Akasaki). Both singles for the opening and ending themes were released on October 22, 2014. The anime has been licensed for streaming in North America by Funimation, and in the Middle East, North Africa and Europe (excluding United Kingdom and Scandinavia) by Crunchyroll, and AnimeLab in Australia and New Zealand.