one of the authors notes (late dxd/ early arifureta) said he was NOT going to add ANY Chinese cultivation novels into the story. that means NO ATG, tales of demons and gods, battle though the heavens or any others like that. I will say it would be interesting to see how they would be integrated into the story but it would only really be to make a massive increase in the harem and/or for the final bosses of those novels (ATG god kings, TDAG supreme sage etc.) to be the only real threat to him and his girls while there and would have no purpose otherwise