High School DxD EX

High School DxD EX (ハイスクールD×D EX Haisukūru D×D EX) is a six part special novel released with the Blu-Ray volumes of the third anime series, High School DxD BorN.

Summary
From this point on, what is told consists of top secret circumstances known only to a small number of highly important people—

Though these are important events, it is something that must not by any means be made public……the time may come though when the truth contained within this information may be useful.

Therefore, in the case that something were to happen to me, I am purposefully recording this to serve as an intermediary.

Even though I earnestly desire that this shall never be released, I shall commence the account.

―○●○―

The story is told from Azazel's perspective where he recorded the following events. The Occult Research Club faces off against invaders known as Underworld Lifeforms led by Loki that has travel from a possible future 30 years from now, however also from the future comes a surprise visit by Issei's children in an attempt to stop him.

Chapters

 * 1 Crimson-haired Sekiryuutei
 * 2 Invaders from Another World
 * 3 A New Church Trio
 * 4 Crimson Will
 * 5 The Forbidden United Front
 * 6 And so, to Tomorrow...

Antagonist

 * Future Loki (ロキ): The Evil God of Norse who returns to the past after cursing Asia. He teams up with the beings from the other world UL to change the past.
 * Ruma Ydura: A being of the Other world Mythology and one of the Four Generals 'Invade Fanatics'.
 * UL: Mechanical beings from the ExE world that are a combination of machine and organic, these beings are soldiers manufactured by the evil gods from the parallel world. They invaded the world the Three Factions resides in the near future before traveling into the past with Loki. Their entire bodies appear to resemble humanoid insects with four limbs, having a hard exoskeleton surface which emitted a brilliant luster and are entirely colored in one shade of silver. They lake neither a nose or a mouth, appear to have five pale eyes and a large protruding head. These lifeforms appear to be durable enough to withstand Koneko's Touki enhanced punch and are capable of shooting a red beam from each of its five eyes that can bypass defensive magic circles, these beams can also curve and redirect their trajectory. Upon their bodies being, these lifeforms produce countless tentacles to reattach and heal them selves.

Other Characters

 * Gasper Vladi: A future version of Gasper who used his time manipulating abilities came back in time along with kids in pursuit of Loki, he also acts as their superior. Gasper has grown to become a more courages man, as well as fearsome as the children both fear and respect him. He also acts as a surrogate uncle to them. He now wears a dark robe and no longer cross dresses, though still speaks in a feminine manner.


 * Issei Hyoudou Gremory: The future version of Issei who is now married to all of the girls who love him, thus achieved his dream to be a Harem King. Issei hardly has time for his children due to his busy scheduled which is filled for the next 200 years, his wives they take turns to see him and act as his escort. He's always rushing over back and forth from one place to another, such as to locations of other mythological systems, whether it's helping out, giving speeches or some kind of industrial enterprise. He is noted to still be a pervert even then.

List of Equipment

 * Boosted Gear Diabolus: Also known as the Gauntlet of the Red Dragon Emperor Crown Prince is an artificial Longinus created by Kurenai based on the the Boosted Gear. It has the same abilities as the original but is still unstable so Ex must be careful not to overuse it.
 * Durandal IV: A Holy Sword manufactured from the union of supernatural and scientific techniques through the use of alchemy and mechanical techniques, and the successor to the original Durandal. It has the qualities of a gun with an ejectable magazine attached and a trigger that launching orbs from the blade similar to Xenovia's  Durandal Cannon.
 * Galatine III: An alchemy-metalurgical crafted version of Galatine, it is used in tandem with Ex's Power of Destruction.
 * Gigantis Maiden Robe: An Artificial Longinus with Fafnir as its power source. This acts as a sort of alternate version to the Down Fall Dragon Spear.
 * Gigantis Blessed Scalemail: The artificial Sacred Gears equivalent to the Balance Breaker known as 'Counter Balance, it creates a golden Dragon armor around Airi that enhances her powers and abilities.
 * Kashuu Kiyomitsu and Yamatonokami Yasusada: Two Holy Swords wielded by Shin. Its name is taken from the actual swords used by the historical Okita Souji.

Trivia

 * All of issei's children who have appeared are those who have come of age to do battle, implying that there are more of his kids who are still young and non-combatants.
 * In their childhood, Issei's kids were tolled the Oppai Dragon Song as a lullaby.
 * With that and the fact that all their mothers had huge breasts, at first they wouldn't recognize someone as a woman if she has small breasts, something which angered Sona.
 * The Nekomata sisters, are technically sibling-cousins, being Half-sisters and cousins at the same time.
 * according to Azazel, their appearance was the same right down to their faces, also implying they were born around the same time.
 * Airi's name was made from combining the initials of her mother Asia, her father Issei, and her step-mother Rias.
 * Ernestine means "vigour, strife".
 * Kurenai means "crimson; vermilion".
 * Kurenai was named by Azazel as an expression of gratitude by Akeno, sort of making him his godfather.
 * Kurenai's Sacred Beast is also known as Fenghuang, the Chinese Phoenix.
 * Shin's name has multiple meanings that could refer to him being part angel such as "heart" or "truth".
 * Robertina means “shining glory”, possibly referring to her inherited powers from the Phenex Clan.
 * Just like her mother Rossweisse, Helmwige is also the name of a Valkyrie in Richard Wagner's play "The Valkyrie".
 * The name Helmwige means "war helmet".
 * Shirayuki means "Snow white" and Kurobara means "Black rose" (although it is spelled with the Kanji for "Black Thorn" even though the pronunciation would be the Kanji "Black Rose"); their very names like their mothers referring to the color of their hair and tails and at the same time, their mothers as well.
 * It's revealed that Le Fay Pendragon has a unnamed son with Issei who was temporally erased due to time being altered, leaving up to his siblings to fix it to bring him back. He's referred to being just as stubborn as Ex.
 * Despite having the ability to wield Caliburn, he decided to be a magician like his mother, which Robertina quotes as a waste of talent.