CallmeMISTER
Explanation will be made, but the signs in the story were delivered very subtle. The mysterious meeting between the mc and 'Hikimage' was very convenient. He was put to face an army of harpies and conquered them too. All of this was premeditated. Even 'Hikimage' giving Rias the magic books was convenient. I had already left parallels in the story and showing that that giant figure and our mc are similar. Including the fact that he is also a Hikikomori. Hikimage= HIKIkomori +MAGE Our mc is the real Hikimage. Angelie is just the one who was doing our mc's orders a long time in the past.
I feel like you're trying too hard to be inception, dxd honestly has more than enough key plot points without adding adozen more before the first arc even finishes it makes the story feel overbloated, i like the general idea but would suggest writing out a timeline and writing around it so as to avoid that, either way all the best. [img=recommend]
Not really a fan tbh. If you suddenly give the mc memories of another lifetime in the past, you're essentially deleting the mc (who we got attached to) and replacing him with someone else. Sure, they might have the same baseline personality, but a person is the sum of their experiences. This is equivalent to pulling a Motohama from the future or an alternate universe and having them replace our mc, in terms of them being the same person. In fact, it's eerily similar to what happened to the original Motohama at the start of this story, with someone absorbing his memories and taking over his body. Not only that, it also pulls the rug out of our expected power progression (one of the main pulls of this story imo) by having a way more experienced character who is already way more knowledgeable about magic take over the mc. I'm gonna put my faith in you and keep reading since the rest of this story has been really good so far, but I honestly don't have high hopes, unfortunately. A plot twist isn't always a good thing, especially when the story before the plot twist could already stand on its own two legs.