Chapter Zero is the first official chapter of the Bloody Cross manga series, which starts off the entire series.
A woman named Tsukimiya positions herself over a corpse she thought she killed and attempted to drink it's blood. When she did, the man jumps up, revealing himself to actually be alive, and scolds her for being an angel attempting to suck the blood of a demon. She retorts this, claiming that she doesn't like to be called an Angel, and stabs him, killing him, and drinking his blood for real this time. When she does, however, she realizes that he's actually just a dummy, and laments that she needs to drink full demon blood soon, or "the curse" will kill her. The head of the dummy, which appears to still be alive, looks up at her and realizes that she's a Half Angel Half Demon, which were rumors that he'd heard for awhile now. He says that, through his eyes, "Lord Brass" can see and hear everything.
She then thanks him, claiming that thanks to him, she now knows that the real Lord Brass is nearby. Hinata is first seen at some unknown located, shortly after he apparently dispatched single handedly quite a few dummies who he thought were full blooded Demons, whom he wanted to drink their blood of. Angry tha the keeps falling for this dummy trick several times, he laments how he underestimated someone named "Brass." He also claims that he doesn't know if he can take on a full blooded demon on his own, but that he still has to do it anyways. Hinata then hears a noise and questions what it is. When nobody answers, he fires a blast of magic at it, and ends up hitting Tsukimiya. Tsukimiya calls him a brute and then mentions Brass, peaking his interest. He asks her if she's an Angel hunting Brass, and she responds by saying to stay away from him, because he's her pray. Hinata then introduces himself as a full Angel, and claims that he wants them to work together to hunt Brass.
However, Tuskimiya refuses, claiming that, as a half Angel, she can sense lies, and she doesn't trust him at all. She then procoeeds to leave, telling him not to get in her way. Before she can get away, however, both of them feel a strong demonic presents coming their way. Hinata fires some tracking spell at the direction it's coming from, but still appears to have trouble tracking it. He tells Tsukimiya this, but she still refuses to cooperate with him. She then falls to the ground due to the pain that her curse is causing her. The two of them then flee to inside of a building so that Tsukimiya can rest up. Hinata explains that his spell is currently tracking Brass's location, so they can move out when that's been completed. Tsukimiya questions why he's helping her when she still doesn't trust him, and he explains that he's trying to earn her trust. To do that, he'll even nurse her back to health if she collapses. When Tsukimiya brings up her ability to detect lies, HInata throws her down and instructs her to worry about herself.
He informs her that she'd stand no chance against a pure blood in her current state, so they should work together to do it. She then shows Hinata the half blood curse on her left breast, and explains the conditions of the curse to her. She says that God cannot forgive an Angel who would choose to bread with a Demon, and therefore their offspring is branded with this curse at birth. She explains that, in order to live, she has to drink pure blood demon blood before she turns 18, and she has little time left. Understanding now, Hinata attempts to examine the curse himself to see if he can remove it for her. He first licks the mark on her breast, giving him an embarrased look out of Tsukimiya, but then he casts a spell on it, which is supposed to get rid of the pain, at least temporarily, causing Tsukimiya to thank him. The two of them have some more humorous banter, which involves HInata calling Tsukimiya cute. After that Tsukimiya does agree to work with Hinata after all, in order to show her gratitude to him. Tsukimiya and Hinata then head inside of a certain building, Hinata noting that there's lots of Angel bones, probably form Angels that were eaten by Brass, Tsukimiya also noticing the remains of wandnering souls corrupted by hatred.
The two of them are then largely surprised by the arrival of Brass, who criticizes them for criticizing him about his "cute possessions" as he puts it, after he invited them to that building. When Brass says he'll make them his food as compensation, Hinata responds by saying that he too must atone for his sins for being a man eater. Tsukimiy and Brass then begin a short battle, involving Brass summoning dead skeletons back to life to fight for him, and Tsukimiya drawing her sword and using it against him in combat. When it looks like Brass is about to get the upperhand int he fight, Tsukimiya turns the tables on him by using her blood that he spills to fight him, causing serious damage to him.
The battle led up to Brass launching a finishing blow to Tsukimiya, but Hinata jumping in to take the blow to save her, at the dangerous risk of his own life. What he really did, however, was launch a double body spell, creating two of himself, so he could save Tsukimiy anad still live himself. In the end, Tsukimiya uses her blood control to rip Brass apart, finally killing him. When Tsukimiya went in to drink Brass's blood, she fell to the ground in pain. Hinata apologized to her, revealing that his true intentions were to take Brass's blood for himself, due to him also being a half blood demon. Before Tsukimiya dies she convinces Hinata to kiss her. However, this was just a trick. When they kiss, she drank his blood, and thus drank Brass's demon blood inside of him. Unfortunately, the mark rejected the already used demon blood she drank, and what's worse, the mark divided between the two of them, so they both still have their curses now. While Hinata appears to be oddly optimistic about the situation, Tsukimiya hates it, claiming that it doesn't seem like they'll live for much longer.