Hmmm? You're asking for a method of resurrection?
(As he made that statement, the last word seemed slightly high-tone, providing evidence that he's intrigued by the prospect.)
You're the kind of person that's rare these days, a young kid that's interested in learning the methods of resurrection. Okay, I will give you as much information as possible.

Resurrection usually refers to an act where after the body expires, the memory stays intact as the spirit transfers to another body. Yes, this means no such transfer can occur unless the body expires. However, that does NOT mean the new body has to be that of a newborn.

If the body is devoid of spirit, or if the spirit is severely weakened, it is possible that your spirit can enter that body and control it like it's your own.
(What...!? I couldn't believe what I just heard, so I paid extra attention to what Alcaster had to say)

The body that absorbed your spirit becomes one with the spirit's identity, which means the spirit can control the body's mind and thought. Basically, your spirit can control the body's every move by being one with the body. This all works as long as the body is healthy. If the body is damaged, then the moving part does not work.

(So... this is how Asia's theory is backed up...!
Dunas basically stole the comatose Marr's body, and pretended to be Marr's doctor to give out orders to Core Blaze
As if it's the words of Zipangu that it is adhering to...!)

(I'll need to notify this to Asia ASAP, or else...! Should I say goodbye to Alcaster and return to Asia immediately...?)

(I bid adieu to Alcaster and returned immediately to Asia)

(Should I gather up more information on this matter...?)

So how was the conversation? Were you able to meet Alcaster...!?
(She must have been very concerned, from the way Asia greeted me. I told her everything I heard from Alcaster)