Will was born in the city of the dead, where he was raised by three undead. Although he was nurtured with love, Will questions his existence in this life-forbidding place where he is the only human alive. He discovers his three parents are secretly hiding something that may explain this mystery, and as if this weren't puzzling enough, he has yet to discover that still more secrets lie within him.

Five years have passed since Will learned Mary's secret, and he is now 13. His undead parents' lessons grow ever more difficult, but Will manages to stick to it. One day, Blood gives him an assignment requiring him to escape from the ruins in the city. Will desperately tries to fight his way out, but an odd sensation of malice stops him. It turns out that malice was coming from an unexpected source.

Turning 15, Will challenges Blood to a fight with real swords as his coming-of-age ceremony, but Gus asks Will to lose on purpose. Will doesn't get a chance to ask Gus about what happened that day in the ruins before he must head into his battle against Blood.

The "God of Undeath" Stagnate's sudden appearance catches the three undead off-guard. Although his attempt to abduct Blood and Mary is interrupted by Gus, the black mist bursting from his chest leaves them no time to feel relieved. Will is unable to do anything as Stagnate says to him with a fearless smile, "It's all thanks to you."

On the verge of death, Will swears an oath to Gracefeel and rises to challenge Stagnate again. However, Stagnate tricks Will into fighting his shadow while he goes off to attack Blood and Mary. When he realizes what's going on, Will rushes back to the Temple and arrives just as Stagnate comes within reach of the two wounded undead.

Will departs from the city of the dead and sets foot in the outside world. After walking in the woods for several days, the first being he meets is Menel, a half-elf hunter. Will is delighted to talk to someone his own age and continues to recall it even after they go their separate ways. That night, he receives a revelation from Gracefeel.

Menel leads Will to a village that's being attacked by monsters. As he banishes them, he learns gravity of the tragedies caused by the attack. Piled-up bodies and burnt houses are everywhere. Then, from their midst, a faint voice catches Menel's attention. The voice belongs to a severely burnt young boy who has turned undead.

Having saved the village from the Demon's attack, Will and Menel decide to head toward the city of Whitesails, a booming trade center. As they pass through Beast Woods, they suddenly hear a scream. Running in its direction, Will and Menel see two travelers being attacked by a Giant Ape.

Bii and Tonio have joined Will on his journey, and the party finally arrives in Whitesails. Will has never seen such a big, lively city, and he is deeply impressed. He hopes to relieve the exhaustion of his journey, but suddenly, an alarm sounds. He hurries outside and sees a massive shadow flying directly over his head.

Will is summoned to meet with Ethelbald, the lord of Whitesails, who refers to him as the "Wyvern Slayer." He offers to gather private soldiers so he can stop the damage caused by all the beast attacks in the area. Will's sudden proposal earns a cold reaction at first, but after a closer look at Will, Ethelbald grants him permission. So Will enters the Whitesails tavern in search of reliable allies.

Having been anointed as a Paladin, Will turns his focus to rebuilding the village and exterminating monsters. One day, one of Will's patrol parties goes missing. When Will, Menel, and "the Penetrator" Reystov return to Beast Woods to search for it, they discover the scattered remains of his comrades. Sensing something is wrong, they proceed deeper into the valley.

Will and his comrades narrowly escape the beasts' trap. Seeing how badly Menel is injured, Will realizes that his capabilities surpass those of his comrades, causing him to put them in danger without even knowing it. Clouded by self-reproach, Will goes to fight the beasts alone, but Menel angrily stands in his way.