There wasn't an official synopsis so I put one together for you from the information that I could find.
This show is a spin-off from the classic anime Saint Seiya (animated adaptation of Masami Kurumada's manga). The original Saint Seiya is said to be a story about 5 warriors, named the "Saints". They fight wearing sacred armour called "Cloths" and each design derives from the constellation that the character has adopted as their guardian symbol, by a mystical energy called "Cosmo". They are sworn to defend the reincarnation of Athena, the Greek goddess, throughout her battle against the Olympian gods who want to take over Earth.

Further information:
Episodes: Unknown
Aired: 2015 to ?
Producers: None found, add some.
Genres: Action, Adventure, Fantasy, Sci-Fi, Shounen

Betrayed from within and overwhelmed by dark sorcery, the valiant armies of Pars are overrun by the warrior-fanatics of Lusitania. Escaping the destruction of his homeland, the heroic Prince Arslan begins to assemble a group of five, extraordinary allies—a priestess, an exiled warrior, a mischievous minstrel, an insightful artist and his attendant—to aid him in his fight against the Lusitanian invaders. Together, they must build an army and defeat 300,000 trained soldiers—including the mysterious Lord Silver Mask—who has also laid claim to the throne of Pars.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Unknown
Genres: Action, Adventure, Drama, Fantasy, Historical, Supernatural

This synopsis is for the first season but it still applies.

Maruo Eiichirou (Ei-Chan), a first year honor student, one day decides he's unhappy with the way things are and lacks exercise. He finds a flyer for the Tennis Club and decides to check it out. He's instantly captivated by it. With no prior experience and poor physical conditioning, join Ei-Chan as he embarks on a tennis journey using his smarts, dedication, and work ethic.
Read more at http://myanimelist.net/anime/21185/Baby_Steps#1mpIYRTxxdxLdhgZ.99

Fifteen years after the summer vacation. If we didn't go to the Digital World. If I didn't make this trip with others. If we didn't change at all like this. These Digimon were always with us. We've been friends all the time. We learned the importance of helping each other. All the things have made us what we are!
New stories for all the "DigiDestined" in the world. Taichi, seventeen, high school days.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Toei Animation, Bandai
Genres: Action, Adventure, Comedy, Kids
Rating: PG - Children

Commonly known as the "Dungeon," the city of Orario possesses a huge labyrinth in the underground. Its strange name attracts excitement, illusions of honor, and hopes of romance with a pretty girl. In this city of dreams and desires, new adventurer Bell Cranel has his fateful encounter with the tiny Goddess Hestia. Thus begins the story of a boy striving to become the best adventurer and a lonely goddess searching for followers both hoping to reach their goals and perhaps have some romance in the side.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: J.C.Staff, Genco
Genres: Action, Adventure, Comedy, Fantasy, Romance

The anime's story revolves around Nya-tan, the cat of Chinese astrology who wants to become a member of the Chinese zodiac. Nya-tan is simple and suffers from memory loss, and she tries various foolish ways to become a member. She meets Takeru Tendo, a high school student who lives alone in Akihabara, and becomes a freeloader at his house. Little by little, she gets closer to her goal.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Shirogumi, Encourage Films
Genres: Shounen

There is no separately released synopsis for this show as it is only the second season of an existing show. Here is some relevant information about the existing show:
Shirō Emiya, a high school student and amateur magus living in Fuyuki City, Japan, is dragged into the Fifth Holy Grail War, a secret magical tournament. In it, seven participants, known as Masters, and their Servants, reincarnated personifications of legendary heroes of history, fight in a battle royale for the Holy Grail, an omnipotent magical chalice that can fulfill any wish or desire for its victor.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Aniplex, ufotable, Aniplex of AmericaL
Genres: Action, Fantasy, Magic, Shounen, Supernatural
Rating: R - 17+ (violence & profanity)

The Gintama event at Jump Festa 2015 announced on Sunday that a new television anime series has been green-lit. The new series will premiere on TV Tokyo and its affiliates in April 2015.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Sunrise, TV Tokyo, Aniplex
Genres: Action, Comedy, Historical, Parody, Samurai, Sci-Fi, Shounen
Rating: PG-13 - Teens 13 or older

Roughly a year after his arrival at Mihama, Yuuji makes the unexpected decision to pursue promotion within CIRS. The action resumes with Yuuji in a meeting with JB at "corporate HQ," discussing the documents he submitted for review as a part of the promotion process—said documents pertaining to none other than Yuuji's own past. Meanwhile, back at the dorm, the girls find themselves unwittingly following along after Sachi and Makina restore the shredded rough draft of said documents.

The irony, of course, being that prominent figures in Yuuji's past may just be continuing to exert their influence upon the present...

Further information:
Episodes: Unknown
Aired: Mar 2015 to ?
Producers: Frontier Works, 8bit
Genres: Drama, Romance, School, Harem, Psychological

I would recommend looking up the game "Gunslinger Stratos" to find out what this is really about. There's a bunch of information on wikipedia. This is just the anime adaption from the game.
The story revolves on a group of gunslingers, each from the two universes who participate in Operation Stratos, particularly on a group of four childhood friends: Tohru Kazasumi, Kyōka Katagiri, Kyōma Katagiri, and Shizune Rindo, who all must confront their own flaws and differences when they battle their alternate selves in order to survive.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: A-1 Pictures, Square Enix, Nitroplus
Genres: Action, Sci-Fi

This is the second season of Kiniro Mosaic.
Here's the synopsis from the first season:
The story begins with Oomiya Shinobu, a 15-year-old, seemingly pure Japanese girl who actually did a homestay in Great Britain. Even after coming back to Japan, she still misses her time overseas. One day, an airmail letter arrives from Alice, the girl in Shinobu's host family in Great Britain. The letter reads: Shinobu, I'm coming to Japan! The Japanese/British girls' mixed comedy follows the lives of Shinobu, Alice, and other girls from both Japan and Great Britain.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Studio Gokumi
Genres: Comedy, School, Slice of Life
Rating: PG-13 - Teens 13 or older

The anime begins when Kumiko Oumae, a girl who was in the brass band club in junior high school, visits her high school's brass band club as a first year. Kumiko's classmates Hazuki and Sapphire decide to join the club, but Kumiko sees her old classmate Reina there and hesitates. She remembers an incident she had with Reina at a brass band club contest in junior high school...

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Kyoto Animation, Lantis, Pony Canyon, Rakuonsha
Genres: Music

The third season of High School DxD based on the light novel series by Ichiei Ishibumi.
Here is the synopsis from the first season:
Issei Hyodo is your average perverted high school student whose one wish in life is to have his own harem, but he's got to be one of the unluckiest guys around. He goes on his first date with a girl only to get brutally attacked and killed when it turns out the girl is really a vicious fallen angel. To top it all off, he's later reincarnated as a devil by his gorgeous senpai who tells him that she is also a devil and now his master! One thing's for sure, his peaceful days are over. In a battle between devils and angels, who will win?

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Genco, Lantis, TNK
Genres: Action, Comedy, Demons, Ecchi, Romance, School, Shounen, Harem
Rating: R+ - Mild Nudity

Second season of Kaitou Joker series.

The thief Mysterious Joker doesn't just steal things. An audacious and elusive miracle-maker, he travels the world searching for treasure with his partner and cook Hachi. As they circle the globe, they must avoid traps set by the police and compete in various competitions to reach their final goal, the Timeslip Treasure.

Further information:
Episodes: Unknown
Aired: Apr 6, 2015 to ?
Producers: Asatsu DK, Shin-Ei Animation
Genres: Adventure, Comedy, Mystery, Shounen
Rating: G - All Ages

A breach between Earth and the netherworlds has opened up over the city of New York, trapping New Yorkers and creatures from other dimensions in an impenetrable bubble. They've lived together for years, in a world of crazy crime sci-fi sensibilities. Now someone is threatening to sever the bubble, and a group of stylish superhumans is working to keep it from happening.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Bones
Genres: Action, Adventure, Fantasy, Super Power, Vampire, Supernatural, Seinen

The story is set in a world where humanity, driven off the land by the threat of magical armored insects, now live in aerial floating cities. Thus wizards—aerial combat mages who fight the insects with magical powers—came into being.

Kanata Age is a young man who lives on the floating wizard academy city of "Misutogan." He was once celebrated as the "Black Master Swordsman," the elite ace of the S128 special team; however, he is now despised as the "traitor of the special team." One day, he is assigned as the instructor of E601, a team that has suffered ten consecutive defeats. E601 has three girls—Misora Whitale, Lecty Eisenach, and Rico Flamel—with one or two peculiar quirks.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Diomedea
Genres: Action, Drama, Fantasy, Magic, School

As a child Sakura Mamiya mysteriously disappeared in the woods behind her grandma's home. She returned whole and healthy, but since then she has had the power to see ghosts. Now a teenager, she just wishes the ghosts would leave her alone! At school, the desk next to Sakura's has been empty since the start of the school year, then one day her always-absent classmate shows up, and he's far more than what he seems!

Further information:
Episodes: 25
Aired: Apr 2015 to ?
Producers: NHK, Brains Base, NHK Enterprises
Genres: Comedy, Romance, School, Shounen, Supernatural

Lupin will be starring as the main character in this upcoming series set to take place in Italy and San Marino.

Reflecting its setting, the anime will debut in Italy before airing in Japan. Lupin III fans will note that the titular thief now has a blue coat, following his earlier appearances in green (first series and some OVAs), red (the second series as well as most films and television specials) or pink (third series).

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: TMS Entertainment, Telecom Animation Film
Genres: Action, Adventure, Comedy, Shounen
Rating: PG-13 - Teens 13 or older

Ninja Slayer is a series of novels which follow Kenji Fujikido who vows to hunt down and kill ninjas after his family is slain during a ninja battle. The stories are set in the futuristic city of Neo Saitama.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Trigger
Genres: Action

This is the second season of the show. Here is the synopsis from the first season:
Raku Ichijou is an average high school student. He also happens to be the sole heir to the head of a Yakuza Family called the Shuei-gumi. Ten years ago, Raku made a promise... a secret promise with a girl he met. They promised one another that they will "get married when they reunite." Since then, Raku never let go of the pendant the girl gave him.

Then one day, a beautiful girl named Chitoge Kirisaki transfers into Raku's class. Their chemistry was more than off. There was not a moment where they were not fighting. But by a weird turn of events, Raku and Chitoge agree to become fake lovers. Although his heart is really interested in his classmate Kosaki Onodera, Raku must continue pretending to be Chitoge's boyfriend.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Shaft
Genres: Comedy, Romance, Shounen, Harem
Rating: PG-13 - Teens 13 or older

Tsuyoshi Takeo is a freshman in high school. (Both estimates) Weight: 120kg, Height: 2 meters. He spends his days peacefully with his super-popular-with-girls, yet insensitive childhood friend, Sunagawa. One morning, on the train to school, Takeo saves a girl, Yamato, from being molested by a pervert. Could this be the beginning of spring for Takeo?

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Madhouse, Nippon Television Network Corporation
Genres: Comedy, Romance, Shoujo

One day, a mysterious virus appeared on Earth which killed every infected human over the age of 13. At the same time, vampires emerged from the world's dark recesses and enslaved mankind. Enter Hyakuya Yuuichirou, a young boy, who along with the rest of the children from his orphanage, are treated as livestock by the vampires. Even in captivity, Yuuichirou dreams big. He dreams of killing vampires. He dreams of killing them all.

Further information:
Episodes: Unknown
Aired: Oct 2015 to ?
Producers: Wit Studio
Genres: Drama, Shounen, Vampire, Supernatural

This is the second season for the show. Here is the synopsis of the first season:
PriPara (Prism Paradise) is the successor to the popular Pretty Rhythm series. The first episode aired on July 5th, 2014. The new anime is set in the Pri-Para world, filled with girls' dreams and yearnings for fashion, dance, and music. Every day, there are auditions that send top idols to worldwide fame on television and online. However, Laala's school prohibits Pri-Para for elementary school children. An unexpected chance leads Laala to make her first entrance into the world of Pri-Para, where she will make her debut. PriPara is also a new game which is replacing Pretty Rhythm. Like Pretty Rhythm, PriPara has an anime which is based off of the game, and has a story line to it. The main characters that we know so far, Laala, Mirei, and Sophie, are also on the game.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Tatsunoko Productions
Genres: Kids, Music, Slice of Life
Rating: PG - Children

There is none released at the moment. I will hopefully update this once I come across one.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: MAPPA
Genres: Comedy, Slice of Life

Amami Hibiki is a girl who can see ghosts and other supernatural phenomena in her surroundings. The stories follow her daily life with both her friends and the otherworldly.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Pierrot Plus
Genres: Comedy, School, Seinen

Yukihira Souma's dream is to become a full-time chef in his father's restaurant and surpass his father's culinary skill. But just as Yukihira graduates from middle schools his father, Yukihira Jouichirou, closes down the restaurant to cook in Europe. Although downtrodden, Souma's fighting spirit is rekindled by a challenge from Jouichirou which is to survive in an elite culinary school where only 10% of the students graduate. Can Souma survive?

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: J.C.Staff
Genres: Ecchi, School, Shounen

This is the second season of the show. Here is the synopsis for the first season.
It's 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. Nagate Tanikaze 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 ultimate battle for the survival of humanity!

Further information:
Episodes: Unknown
Aired: Nov 23, 2014 (first two episodes were streamed at a Sidonia no Kishi event and the rest will air in the Spring of 2015)
Producers: Starchild Records, Polygon Pictures
Genres: Action, Mecha, Sci-Fi, Space, Seinen
Rating: R - 17+ (violence & profanity)

Mochizuki General Hospital boasts some of the most well-trained (and well-endowed) nurses in town. But though these ladies spend much of their day battling sickness, their after-hours are spent fighting a very different sort of disease... Under the leadership of the hospital chairman, a handful of staff members and local teenagers form a group of mercenary assassins, targeting the "cancers" of society and excising those individuals before their wickedness spreads.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Xebec
Genres: Action, Adventure, Ecchi, School, Shounen

An original anime to advertise Urawa City in Saitama, Japan.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Yet to be updated.
Genres: Slice of Life

According to reports by the attendees of Sunday's "Uta no☆Prince-sama♪ Maji Love Live 3rd Stage" event, a third anime adaptation of the otome game "Uta no☆Prince-sama♪" was announced for 2015.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: A-1 Pictures, Showgate
Genres: Comedy, Music, Romance, School, Shoujo, Harem
Rating: PG-13 - Teens 13 or older

This is the second season of the show. Here is the synopsis of the first season.
This romantic comedy revolves around an antisocial high school student named Hikigaya Hachiman with a distorted view on life and no friends or girlfriend. When he sees his classmates talking excitedly about living their adolescent lives, he mutters: "They're a bunch of liars." When he is asked about his future dreams, he responds, "Not working." A teacher gets Hachiman to join the "Volunteer Service" club, which happens to have the school's prettiest girl, Yukinoshita Yukino.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: Feel, TBS
Genres: Comedy, Romance, School
Rating: PG-13 - Teens 13 or older

Ryuu Yamada is a second year student at Suzaku High. Ryuu is always late for school, naps in class and gets abysmal grades. His life is a dead bore. The beautiful Urara Shiraishi, on the other hand, is Suzaku High's brightest student. One day, without explanation, their bodies are swapped! Ryuu ends up in Urara's body, and Urara in Ryuu's.

Further information:
Episodes: Unknown
Aired: Apr 2015 to ?
Producers: LIDENFILMS
Genres: Comedy, Mystery, Ecchi, Romance, School, Shounen, Harem, Supernatural