The Last Immortal's Theorem

"I thought I was doomed to endless despair." Ylledia, an immortal, "trapped" by eternity, feels helpless witnessing her loved ones perish. Her deep sorrow intensifies when she has to let go of the only other immortal in the world. Yet, just as she's losing all hope, a vibrant, golden-haired mortal named Dennis enters her life, suggesting they "link up". The moment Ylledia meets Dennis, a glimmer of hope for the world is rekindled within her. Could this boy be the key to saving the world? Fueled by the newfound hope over their magical connection, Ylledia commits to saving the world once again. (Source: Tappytoon) Note: Includes three extra chapters.