Dies Irae is an urban fantasy visual novel developed by light and was initially released in Japan on the PC as an eroge title on December 21, 2007. Several different versions of Dies Irae were created over the next few years that all added additional story content, these include the "Die Wiederkunft" and "Acta est Fabula" editions in 2009 that both added new character routes as well as visual upgrades. Finally an all-ages version was released in 2012, subtitled "Amantes Amentes," for the PlayStation Portable which featured further enhancements, new material and the removal of all adult content. Ports of Dies Irae: Amantes Amentes were also released for the PC in 2012, Android devices in 2015 and finally iOS in 2016. Dies Irae: Amantes Amentes was eventually released on Steam in English on June 2, 2017 as a free-to-play title where the player could read through the game's common route for free but would have to purchase the character routes separately. The routes were divided into two separate DLC packs with the first part containing the routes for Kasumi & Marie and part 2 having Kei & Rea.
Dies Irae was also adopted into several other mediums after Light began several projects to expand the IP, including an crowd funding campaign to create an anime TV series in 2015, which later aired in 2017, along with the creation of various side-stories published around the same time in the form of drama CDs, manga, etc. The English edition of Dies Irae: Amantes Amentes was crowd funded as well through a Kickstarter in 2017 that funded the game's localization along with a port for the PlayStation Vita thanks to the campaign reaching several stretch goals.
In 1945, a small group of individuals called "Longinus Dreizehn Orden (13 Holy Lancers)," as known as the knights of the Black Round Table, conducted a mysterious ritual where they used the souls of those who perished in the flame of the fallen Berlin as the sacrifice to create what they call "the Holy Ark," and disappeared. In 2006, those of the Black Round Table have returned in order to accomplish their objective, to re-write the current world system.
A socially reclusive highschool student, Ren Fujii, finds himself caught up in this midst of their grand scheme. They call him their enigmatic vice commander's agent, "Zarathustra," and seek to hunt him as an integral process of their ritual to resurrect their commander, Reinhard Heydrich. Reinhard, or the so-called Golden Beast and the Prince of Destruction, shall grant wishes of his worthiest knights, and destroy the current world system. Struggling to fight off their pursuit, Ren's peaceful life becomes upside down with confusion and identity crisis. Who is the vice captain of the Black Round Table and Reinhard's sworn friend, "Mercurius" (a.k.a. Karl Krafft, Cagliostro, Hermes Trismegistus, etc.)? What is his true motive? What is the relationship between Mercurius and Ren? What and who is Ren Fujii himself?
When Ren bonds with a cursed soul of mysterious French girl who died by guillotine, his utmost earnest crave to extend his most beloved moment grants him a terrible power. The power to fight the Black Round Table, and the power to transcend from Assiah, Yetzirah, Briah, to Atziluth to rewrite the system of the world.