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.

A look back at Will's experiences and travels thus far.

Under the guidance of Menell, Will goes to a village that has been attacked by monsters. As he subdues the remnants of the demons, the tragedy of the village gradually becomes apparent. A house burned down by piled up corpses. And it was a boy who was burned by flames and turned into an undead (undead) who called out to Menel with a thin voice.

Will and his friends, who travel with Bee and Tonio, finally arrive at the target "City of White Sails (White Sails)". Will is impressed by the big city he sees for the first time and the people who live there. When healing the tiredness of his travels, the bell of an emergency rings. Looking out in a hurry, a big black shadow crosses over their heads--

Will, who was to have an audience with the lord Ethelwald as a "Killing Wyvern," offers to gather private soldiers to eliminate the frequent damage caused by monsters. Ethel once shows an intimidating attitude to such an outlandish offer, but decides to identify Will and forgive it. Head to a bar where adventurers gather to find friends to fight with.

Will, who was appointed as a paladin, was responsible for the reconstruction of the village and the extermination of demons. One day, he goes to "Beast Woods" with Reistov and Menel, who have two names, "Tsuranuki", in order to search for a unit that does not return. He feels something is wrong with the scattered bodies and proceeds to the valley in the back ...

Will and his friends are addicted to the traps of the demons and have routed. After seeing the seriously injured Menel, Will realizes that he has unknowingly put his companion in a dangerous eye, and realizes the difference in ability between his surroundings and himself. It was Menel who showed anger that stood in front of Will who was going to defeat the demon beast alone.

威爾與梅內爾發現至今各地發生災難，原因皆是來自矮人之國的鐵鏽山脈，便持續展開進一步調查。某天，兩人進行每天必做的鍛鍊，發現有一位矮人躲在樹叢裡窺探。威爾以為他有興趣，便主動搭話，但是那位矮人卻欲言又止，然後拔腿就跑。

威爾等人懷著討伐龍的決心，從燈火河港出發，前往鐵鏽山脈。威爾為了反將惡魔們一軍，決定從河川支流逆流而上，繞至山脈的另一側入侵。在途中，威爾順路拜訪了自己的故鄉——死者之街。睽違兩年與伽斯重逢，滿心喜悅，但是……

一行人收下了布拉多遺留下來的英雄裝備，得到片刻休息。伽斯告訴即將前去討伐龍的威爾，想逃避也沒關係。然而威爾搖了搖頭，告訴伽斯他心意已決。伽斯明白了威爾的決心，針對維拉奇爾卡的戰鬥給予建議，目送他們啟程。

一行人終於抵達維拉奇爾卡的所在地，面對壓倒性強大的力量，眾人下定決心與牠決一死戰。但是維拉奇爾卡主動提議，不必戰鬥，收牠為僕從即可。這個出乎意料的提議使威爾陷入混亂，而維拉奇爾卡彷彿在趁勢追擊，向威爾低頭，露出一抹微笑……

威爾與維拉奇爾卡激烈交戰，被逼入絕境。愛用長槍斷成兩截，魔劍也遭到封印，連古雷斯菲露的結界都被粉碎。這時出現在他面前的是不死神矢塔古耐特。矢塔古耐特讓黑鐵之國的昔日矮人戰士復甦，古雷斯菲露鼓舞不復輪迴的戰士們，在威爾等人心中點燃「勇氣」。威爾一行人再次站起，重新下定決心，挑戰最強敵人──維拉奇爾卡！