Shirou is reborn into the DxD universe, and oddly enough, gets the Sacred Gear Blade Blacksmith, not only that, a Subspecies, allowing him to create perfect replicas of swords and Bladed weapons he's seen before. Combine that with the fact he's the only person who know how to use the magecraft Alteration, Reinforcement, and Trace, and the fact he's seen the true Sword of Promised victory, he'll be a true hero in this Age of God's... now if only Alaya and Gaia would stop trying to flirt with him in his dream

In this world, God locked up Alaya and Gaia's wills to affect the world, so they wouldn't cause mass genocide of all the non human races, Gaia can still influence those that use Senjutsu by filling them with her hate and rage. The Alaya of the original world Shirou was from tried to convince this worlds Alaya to send Shirou back to her world, but DxD Alaya has no power to do that, nor does she want after hearing about Shirou's feats, combine that with Gaia being love-starved and over hearing the Alayas conversation wants a piece of Shirou too.

Ideas: -Shirou tried to summon Artoria, but summons Artoria Lily instead, on second attempt he summons Medea, who recognizes him

-Gaia tried to make a move on Shirou by taking control of Koneko, who happens to be starting to like Shirou, this makes Koneko more resilient to Gaia's rage and hate in her power, and fast forwards her developing feeling, qnd increases her magic reserves and mutates her magical core to a higher standard(demi god magical core basically)

- Alaya and Gaia makes themselves look like either Artoria, Rin, or Sakura, experimenting in mixing there appearances to appeal to Shirou... Gaia actually tried adding Taiga, Illya, Irisviel, and Medusa in.

-Shirou still has his Reality Marble, albeit a new version of it, and now a certain Infinity Dragon wants the Marble to herself, despite the sounds of Birds, and light sounds of history echoing from the weapons.

- Shirou takes up Senjutsu thinking it might help keep Gaia out of his head, hes wrong, so wrong

-Shirou's origin and element change due to reincarnation, now its Sacred Sword, meaning now he can choose for himself and has the underlining ability to know if a person is trustable or not.

-Shirou has a Older sister, who is the Reincarnation of Illya, though she hasn't revealed this fact to him, not wanting to remember the fact where she tried to kill her little brother, shes also the spiritual successor of Irisviel, whos basically has a whole Astral from Yugioh thing going on.

-When the Gremory Peerage learn of Shirou's abilitys, Kiba dislikes Shirou purely due to Blade Blacksmiths holy nature, but overtime Shirou breaks Kiba's mindless hate of Holy swords, and asks Shirou to be his Sensei in creation of swords and swordsman ship, Shirou has easily kicked the entire peerage asses before, showing superiority despite being human still.

-Shirou does not get Reincarnated into a devil

- Shirou has unknowingly met multiple Important leaders and Figures in the supernatural world, even being friends with some, not knowing the amount of power they hold.

-Shirou saved Valerie Tepes, and CREATES A NOBLE PHANTASM WITH HIS BALANCE BREAKER, THAT RETURNS THE REMAINING CUPS TO HER, AND UNDOES ALL THE MIRACLES SHE WAS FORCED TO CREATE!!!

-Shirou's balance Breaker allows him to focus on the history of himself or others(people, objects or even locations) around him to create a Noble phantasm.

-Illya, whose name this time is Yukika, is friends with the siscons themselves, Sirzech, Serafall, and Michael(you can not tell me he wouldn't be protective and doting on Gabriel.

-Shirou Accidently summons a Avenger class servant(3 star) who was apparently a angel at one point in her life, her summoned form being when she was first sealed away in hell with out her holy magic or wings, and before her fellow fallen angels developed the demonic magic needed to become Devils, and due to her not revealing her name, Shirou doesn't know who she is, but Michael and Gabriel recognize her, but hold their tongues believing it can't be their sister... Lucifer... oh, and shes basically a little puppy dog when Shirou talks to her, happy to have someone praise her and give her affection.

-Koneko ends up accidenly summoning Asterios, the minotaur, who basically becomes a sibling figure to her. Hes also enhanced due to the attributes of the rook evil piece extending to a Servant.