Irina Shidou

Irina Shidou is one of the many female protagonists of High School DxD and the childhood friend of Issei Hyoudou. She is a devout Christian who, even after learning of God's death, still follows His teachings. She later gets reincarnated as an Angel by the Archangel Michael through one of the Brave Saints, her ranking among his peerage being "Ace".

Appearance
Irina is a young woman around Issei's age with long, light brown hair and violet eyes. Her hair is usually tied into twin side ponytails, each held with a blue scrunchy, but on some occasions she lets her hair down.

She wears the standard Church battle attire, same as Xenovia's with some slight differences. After transferring to Kuoh Academy and moving into the Hyoudou Residence, she starts wearing the Kuoh Academy girls' school uniform, with black shorts under her skirt and an addition of white sneakers with blue accents.

Following her Angelization by Michael, she wears a red "A" printed on her right hand, symbolizing her position as Michael's Ace. Irina also gains white Angel wings, and as of Volume 17, has a total of 4 wings.

Personality
Irina is a cheerful, carefree, upbeat, and enthusiastic person. She's also shown to be cooperative and open-minded to others as she's seen with Arthur discussing about Excalibur Ruler, although he stated that the location is secret.

She's a devout Christian, showing great respect in God's teachings. During her first appearance, she was very harsh towards those who she perceived as an opposition to her religion. This was demonstrated by how she and Xenovia treated Asia when they first met, as well as her reaction to Xenovia becoming a Devil. The death of God of the Bible was a great shock for Irina, yet she still believes in his teachings and transferred her belief to Michael who is the current "God". Irina later became great friends with Asia and the rest of the Occult Research Club members, even joining the ORC herself.

She began experiencing "impure thoughts" around Issei, her Angel wings start to flicker from white to black indicating that she is about to "fall" from her status as a true Angel to a Fallen Angel if she gives in to her desires. She is shown to be very sensitive to and annoyed about being called "self-proclaiming".

History
Not much is known about Irina's history, other than the fact that her family is related to the church, implied to be the Protestant church possessing a currently unidentified Holy Sword. She was Issei's childhood friend and they used to play together before she left Japan and went to England with her family where she trained to become an exorcist. She was eventually partnered with Xenovia.

Birth of the Breast Dragon Emperor
Irina first appears in Volume 3 in a picture with Issei from when the two were playing together. Her first appearance in person was alongside Xenovia under the orders of the Church to retrieve or destroy the stolen Excaliburs from Kokabiel and his men. She was defeated by Kokabiel while infiltrating his base and was left in a near death state by Kokabiel, but was saved by Rias' group and recovered due to Asia's healing. At the end of the volume, Irina takes all the stolen Excalibur fragments back to the church, disappointed at the fact that Xenovia had become a Devil.

She reappears in Volume 6 after being angelized as Michael's Ace she was sent to Issei's Town as the Heaven's representative, and transferred into the same class as Issei, Asia and Xenovia. She then moved into the Hyoudou Residence. When Issei entered his Juggernaut Drive, Irina was the one that brought the Oppai Dragon Song to the battlefield.

The Heroic Oppai Dragon
In Volume 9, Irina goes to Kyoto along with the second-year students of Kuoh Academy. She and the rest of the Occult Research Club then encountered Khaos Brigade's Hero Faction who kidnapped the leader of the Youkais, Yasaka, in an attempt to summon the Great Red. She then fought against Jeanne but was defeated.

In Volume 11, she accompanies the Gremory Team to the Underworld, where they were attacked by Cao Cao and Georg, losing to the two. She was later handed the Excalibur Ruler by Le Fay Pendragon to fix the broken Ex-Durandal after her brother abandoned the sword.

In Volume 12, Irina, Xenovia and Akeno faces Jeanne in a three-on-one match using a prototype Holy Demonic Sword created by the Heaven. While they are able to corner Jeanne, Jeanne manages to take a child as a hostage to prevent them from further attacking her. Luckily, Kiba managed to save the child and Issei defeated Jeanne. After the return of Issei and the defeat of Cao Cao, Irina says she wants to go on a date with Issei, as does the rest of the Occult Research Club.

The Legend of Oppai Dragon and his Lively Companions
In Volume 14, Irina took part in the rescue mission of the Occult Research Club's kidnapped first-years and helps battle the Stray Magicians who took them.

In Volume 15, Irina was seen competing against Xenovia in a swimming match in the underground pool of the Hyoudou Residence for the right to sit on Issei's lap which Xenovia ultimately won.

Irina, along with the rest of the Occult Research Club members, Bennia, and Loup Garou, went to Romania in Volume 16 to aid Rias and Yuuto that were held captive in Tepes castle. She then participated in the attempt to stop the extraction of the Longinus, Sephiroth Graal from Valerie Tepes and rescue her; fighting the enhanced vampires and Grendel along the way. Irina later teamed up with Xenovia to defeat the mass-produced Evil Dragons that were rampaging in the Carmilla's castle town. After returning from Romania, she participated in the meeting for the formation of D×D.

In Volume 17, Irina, along with the rest of the Occult Research Club members, went to the Underworld and participated in the experience day for the school Sona Sitri built located at Auros in the Agares territory. While doing the respective activities assigned to them, Qlippoth managed to surround both Auros and Agreas inside a barrier and announced their intent to attack after a certain period of time. Before the time was up, they reconfirmed their plan and Irina ended up pairing with Hanakai of the Sitri group and fought with the mass-produced Evil Dragons. After the fights were settled and Xenovia's plan to become Student President was revealed, Irina told Issei that the promised season is near.

Powers & Abilities
Master Swordsman: Like Xenovia, Irina is well versed in swordsmanship.

Light Weapons: Being an Angel, Irina can create light-based weapons such as a light sword, a light bow, and arrows.

Flight: Being an Angel, Irina can fly using her wings.

Equipment
Excalibur Mimic (擬態の聖剣（エクスカリバー・ミミック）, Eskukaribā Mimikku): Irina's initial weapon (through artificial means). A Holy Sword that has the ability to transform itself into any shape as its wielder's desires.

Holy Demonic Sword (聖魔剣, Seimaken): A prototype Irina received from Heaven, based on Yuuto's Holy Demonic Sword. She later gained the ability to use different elemental attributes on it, ranging from fire, ice, and lightning.

Quotes

 * "I shall judge your sins! Amen!" (Season 2 New)
 * "I'm not a self proclaiming angel, I'm the real one!"
 * "Amen!"

Trivia

 * Irina's body measurements are B87-W59-H89 cm. (B34-W23-H35 in.) and her height is 164 cm. (5 feet 4 inches), according to the visual book with her data.
 * Among all the girls, Irina has known Issei for the longest time.
 * Irina has become well-known for calling herself an "Angel", thus gaining herself the title "Self-Proclaiming Angel". As a vindictive insult, she has been recently called the "Self-Proclaimed Childhood Friend".