Idea 20 gunbuster x doctor stone x DxD

At least a Polly with femSirzechs and Grayfia could become a harem later on

The time line is kinda like a Time Turner don't really know any movies or shows to explain it

Issei and his twin Himiko were adopted by the Hyoudou who are half devil's(lucifer) half youki(thier parents are also half bloods) Issei could take after thier father and is a Inugami while Himiko could take after thier mom and be a Yuki Onna that were sealed for thier protection turning them human. Issei is not a pervert it is a facade while Himiko becomes an Ice queen😈. Issei still becomes Rias's pawn but Himiko could become a fem Sirzechs piece but they have a twin bond so can't be far from one another till thier (Issei) power settles Sirzechs(battlemaniac) trains Himiko and constantly breaks her body for her to settle faster(dxd with a twist inspired) because of this she attains at least high class faster. A little after Issei's power settles after the familiar forest but before Riser Issei is mid-low class because he wasn't actually training they are volunteered and are testing something(it must extend thier life or at least stops physical aging wether its on accident or it was that things purpose) for Ajuka while testing something goes wrong(sabotage by outside magic) and sends them a year before the beginning of gunbuster(past or alternative) where instead of 2 three get chosen while Issei becomes an engineer during the plot of gunbuster the twins stay with Noriko especially when they find out about the time dilation. After the plot the 2 girls could become Himiko's pawns and awaken magic that could summon mecas? Just as the four get settled in thier new life Doctor Stone starts during the time everyone is stoned(😑) mythology resets this way the four and any who join Himiko's peerage from doctor stone can join the war with illusion magic and the only ones that know thier really identity are thier blood and maybe Zeoticus Grimory so this way he can set it up so that Issei and Himiko still become Sirzechs and Rias's pieces and they still go back in time/alternative. It would be hilarious if after the twins are back (they have been gone a week for everyone else) they tell of thier adventures and it turns out Sirzechs and Grayfia had/has a crush on illusion Himiko