The Human Survival Code: Rebirth

Him: A war god in his previous life, he died in battle as cannon fodder.

Her: A top student in her previous life, she sought revenge with the resolve to die.

Him: In this life, a weakling, he fought desperately to find her again.

Her: In this life, a sacred ancestor, at last she can share life and death with him!

This isn't the kind of book that's pure wish fulfillment. I recommend you clear your mind before reading!