In a mist-shrouded city where humans and vampires divide power secretly, outstanding werewolf warrior Ash Grey conceals his werewolf aura, goes undercover under the alias "Grey" as a lowly blood servant to approach the 500-year-old vampire lord Dracula, with the goal of stealing core vampire intelligence to dismantle the rule of the underground world. The two gradually develop true feelings during testing, games and ambiguous interactions. Dracula knew Ash's werewolf identity long ago but deliberately sheltered him, and Ash also destroyed intelligence that would lead Dracula into an ambush many times to protect him. After the werewolf clan launched a general attack using early intelligence, Ash confessed his identity as a werewolf spy, and Dracula did not kill him, but used his own blood to heal Ash who was burned by silver chains. Claudia, leader of the vampire reactionary faction, dissatisfied with Dracula sheltering a werewolf, colluded with radical werewolf leader Fenris to launch a coup, trying to turn warriors of both clans into cannon fodder puppets. Eventually Ash exposed Claudia's conspiracy, persuaded Fenris to put aside the feud and join forces. They quelled the rebellion together, broke the thousand-year-old taboo of confrontation between vampires and werewolves after the war, and established a new order of peaceful coexistence for the two clans.
