High School DxD EX

High School DxD EX is the 4th season of the High School DxD anime series which is based off of the light novels by Ichiei Ishibumi.

Plot
A few months after the events of the last season, Issei and his friends meet a group of teenagers who are Issei's future children who come from the future seeking Issei's help in defeating Scour, the future of the Chaos Brigade and murderer of the children's parents.

WARNING
MAJOR SPOILERS AHEAD IF YOU HAVEN'T READ THE LIGHT NOVELS OR SEEN THE ANIME.

Characters
Issei Hyodo: The series' main protagonist. He was originally a perverted human first-year student of Kuoh Academy until he was murdered by his girlfriend, Yuuma Amano (real name, 'Raynare') on their first date. He was then reincarnated as a devil by Rias Gremory and became her pawn, where he joins the school's Occult Research Club. Issei's original goal was to rise through the devil ranks and become a high-class devil so he can form a peerage of his own and become a Harem King, but since then has apparently given up on that dream after the female Occult Research Club members move into his house.

Rias Gremory: The female protagonist and Issei's primary love interest. A tall, red-haired third-year high school student at Kuoh, and their top idol, she is the leader of the Occult Research Club, which is a front for her devil team, of which she is the King. Known as the and the heiress to the Gremory family of devils, she goes to a normal high school where she doesn't have to flaunt her status. She moves into the Hyoudou Residence after Issei helps break-off her engagement to Riser Phoenix.

Asia Argento: A former priest turned reincarnated devil and Issei's secondary love interest. She was an orphan raised by a Catholic Church where she developed healing powers, until she was excommunicated after healing the Diodora Astaroth. When she moves to Japan, she befriends Issei, but is abducted by Raynare who steals her rings and kills her. After a lengthy battle, Rias revives her to become a devil and serve as her bishop. She is the first female to move into the Hyodo residence and transfers to their school. Despite her devil identity, Asia tries to continue her faith, although whenever she prays or reads the Bible, she initially gets a severe headache. Following the events of the summit in the fourth volume the light novels, Issei is able to get archangel Michael to grant an exception in The System for Asia and Xenovia, so that they can pray as devils to the Church without incurring pain. After Rias (and eventually the rest of the females) move into the Hyodo Residence, she constantly follows the girls' methods of stealing Issei in order to get for herself.

Akeno Himejima: Rias' queen and Issei's tertiary love interest. She is the vice-president of the Occult Reasearch Club. After the death of her mother, Akeno constantly blamed her fallen angel father for her mother's death, until Issei helped them reconcile.

Koneko Toujou: A former nekomata turned reincarnated devil and Issei's quarternary love interest. Formerly known as Shirone, she is a twin-tailed nekomata who was raised by a devil along with her older sister Kuroka. However, her master was by Kuroka after the former began training Koneko to death. Kuroka became a stray devil and Koneko was sentenced to death, until she was saved Sir Zechs Lucifer and became a rook for Rias. She gave Koneko an intense fear and hatred of using nekomata powers. Originally, she hated Issei for his perverted nature and constantly punished him for his perverted actions, but after the latter helped her overcome her nakomata fears, she fell in love with him, although she still tends to punish Issei if his perversion goes too far.

Yuto Kiba: Rias' knight. Kiba is the sole child survivor of the Holy Sword Project, which tries to develop children that can wield the Holy Swords that can destroy devils. He nearly dies from escaping the destruction of the children, but is saved by Rias, and becomes her servant. He enjoys teasing Issei with a yaoi-like romance.

Xenovia Quarta: A former Catholic Church excorcist and Issei's quinary love interest. She was raised and trained in swordsmanship by the swordsman-turned-angel Griselda Quarta. Along with her partner Irina, she was sent to retrieve or destroy the stolen Excalibur swords. When Xenovia discovered that the God of the church no longer existed, she was exiled from the church as a heretic, became a devil for Rias' team as a knight, and joined Kuoh Academy as a first year. She reconciles with Asia Argento for her misdeeds towards her during their first encounter and they become friends soon after. Her goal is to bear children with Issei because they both have strong genetics.

Irina Shidou: A Church follower and Issei's senary love interest. She is Issei's childhood friend, but Issei mistook her for a boy due to her tomboy appearance. Along with her partner Xenovia, she was sent to retrieve or destroy the stolen Excalibur swords. Although saddened that Issei became a devil, she still has feelings for him. After Irina's Excalibur Mimic is taken by Freed Sellzen, she was sent to the Church headquarters to recover, and returned as a representative of the Church to support Michael at the summit. Like Xenovia, her goal is to bear children with Issei because they both have strong genetics, but fears that doing so will turn her into a fallen angel and tries to find a method of doing so without falling.

Gasper Bloody: A cross-dressing male dhamphir (half-human vampire) and Rias' other bishop. Due to his incredibly powerful Sacred Gear, Gasper was sealed until the final third of season 2. He likes wearing female clothing because they look more cute.

Azazel: The leader of the fallen angels. After the peace summit was attacked by the Chaos Brigade, he became the adviser of the Occult Research Club.

Rossweisse: A Norse-magic wielding Valkyrie and Issei's septenary love interest. She originally worked under Odin, but after being abandoned, she became Rias' second Rias, and got a job as a teacher a Kuoh Academy. Unlike most of the girls who immediately had a crush on him, Rossweisse is confused as to whether she was in love with Issei or not.

Ravel Phoenix: The former bishop of her older brother, Riser Phoenix, and Issei's octonary love interest. She followed her brother in the belief that no one could defeat him. After witnessing Riser's defeat, she became infatuated with Issei (albeit with tsundere' tendencies), and later transferred to his school (and moved into his house) so she could spend more time with him.

Orphis: An Ouroboros Dragon/Infinite Dragon God and Issei's nonary love interest. She was originally the leader of the Chaos Brigade, until Scour unleashed a coup d'état and overthrew her. After her defeat, she sought Issei and moved into his house.

Sona Sitri

Genshiro Saji

Riser Phoenix

Yubelluna: Riser's Queen and strongest member.

Mihae: Riser's Bishop.

Karlamine

Siris

Isabela

Xuelan

Ile

Nel

Ni

Li

Marion

Bürent

Shuriya

Mira

Grayfia Lucifuge

Serafall Leviathan

Tsubaki Shinra

Sairaorg Bael

Akuja Beelzebub

Lord Gremory

Venelana Gremory

Millicas Gremory

Baraqiel

Michael

Odin

Vali Lucifer

Arthur Pendragon

Le Fay Pendragon

Bikou

Kuroka

Fenrir

Gogmagog

Ddraig

Albion

Lord Bloody

Matsuda

Motohama

Göndul

Touji Shidou

Mr. Hyoudou

Mrs. Hyoudou

Hayate Gremory-Hyoudou: Son of Issei and Rias.

Miharu Gremory-Hyoudou: Daughter of Issei and Rias.

Jin Argento-Hyoudou: Son of Issei and Asia.

Asuka Argento-Hyoudou: Daughter of Issei and Asia.

Tomoya Himejima-Hyoudou: Son of Issei and Akeno.

Nagisa Himejima-Hyoudou: Daughter of Issei and Akeno.

Kazuya Toujou-Hyoudou: Son of Issei and Koneko.

Moka Toujou-Hyoudou: Daughter of Issei and Koneko.

Ikkou Quarta-Hyoudou: Son of Issei and Xenovia.

Sayaka Quarta-Hyoudou: Daughter of Issei and Xenovia.

Heihachi Shidou-Hyoudou: Son of Issei and Irina.

Houka Shidou-Hyoudou: Daughter of Issei and Irina.

Gouken Hyoudou: Son of Issei and Rossweisse.

Kazumi Hyoudou: Daughter of Issei and Rossweisse.

Daisuke Phoenix-Hyoudou: Son of Issei and Ravel.

Mamiko Phoenix-Hyoudou: Daughter of Issei and Ravel.

Hiroki Hyoudou: Son of Issei and Orphis.

Nana Hyoudou: Daughter of Issei and Orphis.

Junichi Hyoudou: Son of Issei and Kuroka.

Ayako Hyoudou: Daughter of Issei and Kuroka.

Yuichi Pendragon-Hyoudou: Son of Issei and Le Fay.

Sasami Pendragon-Hyoudou: Daughter of Issei and Le Fay.

Scour: The season's main antagonist.