A spinoff mini-series to GARO, ZERO: Black Blood follows Suzumura Rei, the titular Makai Knight ZERO, as he works with two Makai Priests to take down a cult lead by the Horror known as Ring.
A sequel series of sorts, ZERO: Dragon Blood was released in 2017. It's basically Rei on a different mission, with characters like the bartender in Black Blood and Rekka from the main series appearing.
Tropes in this mini-series include:
- Affably Evil: Ring may be running a cult and sacrificing every one in fifty humans to his Horrors, but he's always polite and friendly to everyone, even Makai Knights.
- Anti-Villain: Assuming Ring's intent on using Human Sacrifice to broker peace between Makai Knights and Horrors was genuine, he fits the bill.
- Asshole Victim: One of Ring's prospective victims in Episode 2 is a man named Satoshi who did a hit and run on an innocent woman.
- Played With, as He didn't mean to do it, and shows something of a moral compass when it comes to his lover's safety. He still ran from the consequences, though.
- Nakaima in Episodes 4 or 5 plays the trope straight. Joined the Community to avoid having to give up his organs to his dad's loan shark; and planned on pegging Satoshi's lover as the next Horror sacrifice so he wasn't chosen. Ring found out, and wasn't happy.
- Attack Hello: Yuna introduces herself to Rei by attacking him with a Makai Sword.
- Black and White Morality: Ring, again. It's obvious that he's trying to do some good.....through Human Sacrificial toward his Horror bretheren and taking advantage of those whose lives are in the crapper. Unfortunately, he not only implies that he thinks that Humans Are Bastards, but Ring knows so little about how Human self-preservation works that he's essentially blurred selfishness and self-preservation together; seeing only in terms of what others can give.
- Compelling Voice: Ring's blind singer, who serves to pacify the masses in quite the literal sense. Her song is also what keeps Ring's Horror instincts in check. When she stops singing, Ring transforms into his Horror form, and devours her, being unable to suppress his instincts.
- Even Evil Has Standards: Ring. Bans Horrors from eating Humans without permission and doesn't take kindly to manipulators.
- Expy: Thane Camus as Ring is the closest we'll get to David Bowie as a Toku villain... Outside of Labyrinth at any rate.
- Eye Scream: Right before finishing Ring off, Rei stabs him in the eyes with his swords.
- Good-Guy Bar: The bar that serves as Rei's headquarters. The master caters to a mostly human clientele, but is well aware of Rei's activities as a Makai Knight, and serves as a fairly hands-off handler.
- Human Sacrifice: Ring wants certain Humans to become this to Horrors so that Horror attacks on people will dwindle; possibly stifling tensions between Makai Knights and Horrors.
- Improbable Weapon User: Kain, the other Makai Priest, uses an umbrella to fight.
- Manipulative Bastard: Nakaima. Finds and drugs Satoshi's girlfriend in an attempt to make her the next Dolce sacrifice, that way he isn't chosen. Rei stops him; and once Ring finds out....guess who becomes the next sacrifice?
- Man in White: Ring's schtick. Unlike other Horrors, he dresses in white.
- Woman in White: Iyu, the blind singer who sings the song that calms down everyone.
- Moral Myopia: Despite preaching about how self-serving Humans can be, Ring has no issues manipulating the downtrodden into becoming cattle, using desperate members of his "community" to attack Rei in the Finale, and is fine with exploiting Iyu for her healing song to keep himself in check. He tries justifying it, but nobody's really buying it.
- The Needs of the Many: Ring's mentality concerning the Human Sacrifice he enforces on the Community. Sacrificing some of the population would somewhat safeguard the majority.
- Not in This for Your Revolution: One of the Horror underlings in Episode 4 implies that the only reason they answer to him is because he's supplying them food.
- One-Winged Angel: Ring's Horror form is an enormous winged monster. Also uses a Humanoid version against Rei and co. in Episode 3.
- Power Trio: Right off the bat we have Yuna = Id, Rei = Superego, and Kain = Ego, which is particularly ironic considering Rei used to be the Id to Kouga's Superego and Kaoru's Ego.
- Strong as They Need to Be: An inversion in Episode 2. Yuna is introduced possessing skills somewhere close to Zero's. note She and her partner are then rendered ineffectual against even the most basic of Horror until Rei bails both of them out. They get better in the finale.
- Suicide By Horror: Iyu decides to stop singing and let herself be devoured by Ring as penance for serving him and his ideals for the last decade.
- Utopia Justifiesthe Means: Ring's grand plan. If some Humans give themselves over as Horror sacrifices, the majority of the population won't have to fear Horror attacks; and the Makai and Madou realms can stop fighting. Since this involves Human Sacrifice, the Makai Knights aren't okay with it.