disclaimer: tags/genres grabbed from aniDB and/or ANN. I haven't watched the anime myself yet.
comedy action romance sci-fi school life drama fantasy adventure ecchi short episodes sequel
Keroro

[spinoff], [short 3min]
Majin Bone
Ordinary high school students Shogo Ryojin, Tyrone, Antonio, and Luke are the White Bone warriors. With their special Bone Cards they defend Earth from the evil Dark Bone, who has come from the darkness to destroy our world. However, the true identity of the "enemy" is still uncertain.
sci-fi, proxy battles
Disk Wars: Avengers
In order to capture evil villains, portable capturing devices known as "Disks" were developed. However, thanks to Loki’s machinations, both villains and heroes are sealed up in these Disks and scattered around the world. Amid the chaos, five youths obtained the power to restore these Disks-sealed heroes through a program called "Biocode." These youths received five Disks that Spider-Man, who narrowly escaped being sealed himself, retrieved. Thus, these five can restore Iron Man, Captain America, Thor, Hulk, and Wasp - the Avengers.
Blade and Soul
Alka is an assassin for the Clan of the Sword. She’s on a journey to find the woman Jin Valel, who killed her master Hon. Jin is a demon-like woman who controls the Energy of Chaos and kills without feeling - not unlike how Alka has learned to kill in her work as an assassin. On her journey, Alka encounters three strange women, each great warriors in their own right, and grapples with her slain master’s wish that she leave the life of an assassin behind.
action, RPG
Kantoku Fuyuki Todoki/Insufficient Direction
The everyday lives of mangaka "Rompers" and her husband "Director-kun," also known as "one of four kings of otaku of Japan." Learning to be an "ota-wife" is never an easy job for Rompers.
[short 3min]
Bokura wa Minna Kawaisou
Usa Kazunari, a high school student aspiring to begin a bachelor lifestyle, moves into a new apartment complex only to discover that he not only shares a room with a perverted room-mate that has an obsession for under-aged girls, but also a girl named Kawai Ritsu, a love-at-first-sight, is living in the same building as well!
comedy, romance, slice of life
Akuma no Riddle
Ichinose Haru is a student at a private girls’ boarding school, Myoujou Academy, who is being targeted by 12 assassins disguised as students. Azuma Tokaku is a transfer student and an assassin who also initially targets Haru, but develops feeling for her and decides to protect her from the other assassins.
action, school life
selector infected WIXOSS
In the popular game WIXOSS, there are special cards called LRIGs that few players know about - cards that possess personalities and wills of their own. Ruuko is a teenage girl who just found one of these rare cards. Now, she can use her LRIG to battle in a strange, dark plane of existence. If she wins, her wishes will be granted - but what happens if she loses?
proxy battles
Kenzen Robo Daimidaler
The comedy centers around a high school boy named Madanbashi Kouichi who has Hi-ERo particles, the power source to operate the robotic weapon Daimidaler. With the help of Sonan Kyouko from the mysterious Prince Beauty Parlor organization, he stands up against the Penguin Empire that troubles humanity.
comedy, ecchi, mecha
Seikoku no Dragonar
Ash is a student at Ansalivan Dragon Academy, attended by children who have formed contracts with dragons. He possesses the "star mark," the sign of a contract, but since his partner hasn’t been born yet, he seems insignificant. The awakening of the dragon he’s raising inside his body is triggered by an incident, and it emerges in the form of a young girl.
fantasy, ecchi, harem, school life
Mahouka Koukou no Rettousei
In a world where magic is not a fairy tale but has existed for one hundred years siblings Tatsuya and Miyuki Shiba prepare to begin their studies at the elite Private Magic University Affiliated High School (Magic High School for short). Entering on different levels of the academic spectrum the two turn the once peaceful campus into a chaotic one.
action, magic, romance, school life
Kamigami no Asobi
Yui Kusanagi is ordered by Zeus, a god and the headmaster of a school he created, to teach the meaning of love to young and handsome gods. The reason he has for doing this is to cancel the negative effects of the weakening bond between the world of the divine and the world of the humans.
shoujo, supernatural, reverse harem
Captain Earth
One night right before summer vacation, Manatsu Daichi, a second-year in high school, sees a weird round rainbow floating in the sky above Tanegashima and ventures there alone. He has seen this rainbow before. With the memories of his father’s mysterious death and an encounter of a mysterious boy and girl, Daiji arrives on the island while the alarm of a building labeled Earth Engine is going off. Someone asks him if he’s a captain, just as robotic intruders from Uranus called Kill-T-Gang arrive. The battle around the shining stars is about to begin.
sci-fi, mecha
Soredemo Sekai wa Utsukushii
Nike, the fourth princess of the Rain Dukedom and one who holds the power to call forth the rain, travels to the Sun Kingdom to marry Sun King Livius for her country, despite her own reluctance. She soon discovers that the King, who conquered the world in only three years after his ascendance to the throne, is still a child! Furthermore, for trivial reasons, he has demanded that Nike call forth the rain...?!
fantasy, romance
Abarenbou Rikishi!! Matsutarou
The story follows Sakaguchi Matsutarou, a giant roughneck man with strength far beyond ordinary people. He never uttered words like work hard, strive, and dream like the typical shounen manga protagonist. However, he is stronger than anyone and peerless in sumo wrestling. His greatest weakness is his own carefree personality. He grows into a full-fledged sumo wrestler.
sports
Haikyuu!!
A chance event triggered Hinata Shouyou’s love for volleyball. His club had no members, but somehow persevered and finally made it into its very first and final regular match of middle school, where it was steamrolled by Kageyama Tobio, a superstar player known as the King of the Court. Vowing revenge, Hinata applied to the Karasuno High School volleyball club... only to come face-to-face with his hated rival, Kageyama.
sports
Baby Steps
The story follows Ei-chan, a punctual and earnest boy who has strived for straight As since elementary school. He began going to a tennis school during high school. There, he meets Natsu, a beautiful, earnest girl who only has passion for tennis.
sports
Gokukoku no Brynhildr
A high school senior Murakami Ryouta had a childhood friend called Kuroneko who died in an accident. Ryouta had made a promise with Kuroneko that he will prove there are aliens in the universe. In order to fulfill his promise, he joined the astronomy club at the school as its only member and kept observing the stars almost every night. One day, a girl who looks like Kuroneko transferred into his class. To his surprise, the girl’s name is Kuroha Neko which is really similar to his childhood friend’s name. However it seems that there is something unusual about her. It turns out that she is a witch who actually escaped from a research laboratory.
sci-fi, fantasy, mystery, harem
Isshuukan Friends.
Yuuki is a boy who wants to become friends with his classmate and desk neighbour Kaori. However, she gently declines his friendship, saying: "But, my... memories of my friends disappear in a week..." Even so, Yuuki wants to become her friend, and so the two become friends over and over again as the weeks pass.
comedy, slice of life
Kanojo ga Flag wo Oraretara
Hatate Souta is a boy with the unique ability to see Flags above the heads of other people. The Flags mark critical crossroads in people’s lives . when the choices they make will determine love, friendship, victory, and even death. He transfers to Tokyo’s elite Hatagaya Academy, but instead of living by himself in the boys’ dormitory, he ends up living with five beautiful girls under one roof.
comedy, harem, school life
Oreca Battle
Young boy Faiya Orega loves Oreca competitions. One day, he is granted the power to summon real Oreca monsters due to the mysterious powers of the treasure chest Pandora. To protect the peace of the Oreca world, Faiya must fight the demon king who threatens the land.
[short 10 min], proxy battles?
Dragon Collection
Through an unexpected turn of events, an ordinary elementary school student, Enryuu Hiro, finds himself in the world of the Dragon Collection game. This is a world called Dragon Earth, where gods, humans, and monsters exist side by side. Those who roam this world using a magic book, called a Grimoire, and cards to summon monsters and search for treasures that bear the powers of dragons are called Dracolle Battlers. Despite his bewilderment, Hiro becomes a Dracolle Battler and, together with the friends he meets there, begins his adventure to become a legendary Dragon Master!
[short 15 min], proxy battles
Hero Bank
In a not too distant future, a cybernetic game called "Hero Battle" allows users to download wearable fighting suits and compete in cyberspace. Fifth grader Kaito Koushou is one of many players, and he has one more reason to win the championship: the 10 billion Yen prize to pay the 10 billion dept on his shoulders.
tournament
Mangaka-san to Assistant-san to
The story depicts the work-life of a perverted mangaka, Aito Yuuki, and his assistant, Ashisu Sahoto. Constantly pressured by his editor and lacking experience with girls, Aito asks Ashisu to act as a reference
comedy, ecchi, [short 15 min]
Mahou Shoujo Taisen
Magical girls from 47 prefectures of Japan gather together to protect their respective local characteristics.
magic, [short 4 min]
Black Bullet
In the year 2021, mankind was decimated by an epidemic of a parasitical virus named Gastrea; the survivors were forced to live within Monoliths, structures created from Varanium, a metal that is able to subdue the virus. People then discovered the existence of Cursed Children, children born with the Gastrea virus who are able to control it, which gives them superhuman abilities; due to the virus’ intervention, however, the Cursed Children could only be female. Groups known as Civil Securities were formed to specialize in fighting against Gastrea; they operated by pairing an Initiator, who is a cursed child, and a Promoter, whose job is to lead the cursed child. Ten years after the epidemic, Satomi Rentarou, a high school student who is also a Promoter in his childhood friend Tendou Kisara’s Tendou Civil Security, and his Initiator, Aihara Enju, receive a secret mission to prevent the destruction of the Tokyo Area.
action, mystery, sci-fi
No Game No Life
Sora and Shiro, a brother and sister whose reputations as brilliant NEET (Not in Education, Employment, or Training) hikikomori (shut-in) gamers have spawned urban legends all over the Internet. These two gamers even consider the real world as just another crappy game. One day, they are summoned by a boy named God to an alternate world. There, God has prohibited war and declared this to be a world where everything is decided by games - even national borders. Humanity has been driven back into one remaining city by the other races. Will Sora and Shiro, the good-for-nothing brother and sister, become the Saviors of Humanity on this alternate world? "Well, let’s start playing."
comedy, fantasy, ecchi
Hitsugi no Chaika
Toru Acura is a 20-year-old retired soldier meandering through life now that the war has ended. He encounters Chaika Trabant, a 14-year-old sorceress carrying a coffin, and follows her in hopes of finding meaning to his life again. The two travel with Toru’s adopted sister, Akari, the employed member of the group and thus Toru’s source of income.
adventure, comedy, fantasy, romance, bounty hunters
Fuuun Ishin Dai Shougun
In the late Edo period, Japan had experienced an unprecedented crisis by Kurofune (Black Ships), the ships from foreign countries. But a giant robot called Onigami, which has existed since ancient time, dispelled the Kurofune ships and the exclusion of foreigners was accomplished. The story begins in Japan where Meiji restoration in 1868 didn’t happen.
action, mecha, ninja
Escha & Logy no Atelier: Tasogare no Sora no Renkinjutsushi
This world has gone through many Dusks, and is slowly nearing its end. Within this world, in the western reaches of the Land of Dusk, there was a nation that prospered thanks to its use of alchemy. There, in order to survive the eventual arrival of the Dusk End, the people devoted their efforts to rediscover and recreate lost alchemical technologies. Rediscovered technology from the past era was gathered in the alchemy research city known as Central, where research was conducted on how to halt the advance of the twilight. One of the heroes is a young man who researched alchemy in Central, the other a girl living in a small town on the frontier. This girl’s name is Escha. In the process of using her knowledge of ancient alchemy to help others, she was assigned to the Development Department. The young man’s name is Logix. Having learned the newest alchemical techniques in Central, he requested a transfer to this understaffed town to make use of his abilities, and meets Escha when he is assigned to the Development Department as well. The two make a promise to use their alchemy together, and bring success to the Development Department.
fantasy
Gochuumon wa Usagi Desu ka?
Kokoa arrives at the cafe Rabbit House one day, excited for rabbits. She actually all but lives in that cafe. She meets lots of different girls there, including a tiny and cool girl named Chino, a tough and soldier-esque girl named Rize, a spacey and quintessentially Japanese girl named Chiya, and the ordinary but dignified Sharo.
comedy, slice of life
Ping Pong The Animation
Childhood friends Makoto "Smile" Tsukimoto (ironically, he seldom smiles) and Yukata "Peco" Hoshino are capable and aspiring table tennis players of Katase High School. Coach J. "Butterfly" Koizumi has high expectation to both of them, but when Peco gets decisively defeated by a Chinese student he becomes so devastated and stops practicing. Meanwhile, Koizumi discovers Smile’s potential and tries to motivate him to overcome his psychological obstacle.
sports
Inugami-san to Nekoyama-san
Suzu Nekoyama is a timid, shy tsundere girl who loves dogs; her classmate Yachiyo Inugami is a super masochistic, air-headed, friendly girl who loves cats. One day, after a fateful meeting, the two find themselves attracted to each other. In response to Inugami’s instinctive approaches, Nekoyama is always bashful. Their friend Aki has to work hard to make jabs at some of the situations of the two, and also to stop Inugami from going berserk.
comedy, romance, [short 5 min]
Ryuugajou Nanana no Maizoukin
Disowned by his father, Jugo Yama has run away from home to the island of Nanae. He begins to live by himself, only to discover his room is haunted by the ghost of Nanana Ryugajo. She was murdered ten years ago, and her killer must be found before she can rest in peace. Before her death, Nanana collected things from all over the world and hid them throughout the island. Using the mysterious powers of these hidden items, they should be able to find the culprit. As Jugo begins his hunt for her collection, however, he discovers he’s not the only person searching.
action, comedy, romance, ghosts
Sidonia no Kishi/Knights of Sidonia
It has been a thousand years since the Gauna, a strange alien race with no known method of communication, destroyed the solar system. A portion of humanity managed to escape using enormous seed ships like the Sidonia, which have allowed them to maintain the population while drifting through space. Tanikaze Nagate is a young man who has been raised deep in the bowels of the ship. When he goes into training to pilot the huge robotic weapons known as Gardes, Nagate is entrusted with piloting the legendary unit known as Tsugumori. Nagate and his fellow pilots put their lives on the line against the Gauna, in the desperate battle for the survival of humanity...
action, mecha
Mekaku City Actors
The incidents which occurred on August 14th and 15th bring a group of young boys and girls together. They are members of a group they call themselves the "Mekakushi Dan" (Blindfold Organization) and each member possesses a strange power involving their eyes.
mystery, supernatural
M3 - Sono Kuroki Hagane
There is distorted, deep blackness everywhere. That place, in which blackness swallowed everything and took away everything, has become known as the Avidya Zone. Strange beings assume the very form of the despair and chaos of humanity. They are known by this name: Imashime. An expedition surveys the Avidya Zone which consumes human spirits. So, in the intricate intersection between the present in impending crisis and the destiny of the past... can eight boys and girls, assembled to confront the Imashime, find the bright future that lies before the Avidya Zone?
sci-fi
Cardfight Vanguard Legion Mate-hen

[sequel]
Nandaka Velonica

sci-fi, [for kids], [short 10min]
Puchimas!! Petit Petit Idolmaster

[sequel]
Mushishi Zoku-Shou

[sequel]
JoJo no Kimyou na Bouken - Stardust Crusaders

[sequel]
Lady Jewelpet

[sequel]
Fairy Tail

[sequel]
Kindaichi Shounen no Jikenbo Returns

[sequel]
Kiniro no Chord Blue Sky

[sequel], shoujo, reverse harem
Dragon Ball Kai - Majin Buu-hen

[sequel]
Yu-Gi-Oh! Arc-V

[spinoff], proxy battles
Love Live! S2

[sequel]
Break Blade

[re-edit]
Soul Eater Not!

[spinoff]
Date A Live II

[sequel]