The third of the Four Horsemen of the Apocalypse, riding a black horse, is popularly called Famine. The black color of the third horse symbolized death and famine. The rider is shown holding a scale, which represents scarcity of food, higher prices, and famine, likely as a result of the wars caused by the second horseman. Food will be scarce, but luxuries such as wine and oil will still be readily available.
The "a measure of wheat for a penny" from the King James Version of the Bible might not sound like a famine to modern ears, but in the NIV we read "a quart of wheat for a day's wages", which is a little clearer. While it's never identified as his own, it is implied that the voice John the Apostle hears coming from "the third of the four living creatures" comes from the Black Rider, making it the only horseman that actually vocalizes his intentions, the aformentioned raise in prices.
"When He broke the third seal, I heard the third living creature saying, “Come.” I looked, and behold, a black horse; and he who sat on it had a pair of scales in his hand. And I heard something like a voice in the center of the four living creatures saying, “A quart of wheat for a denarius, and three quarts of barley for a denarius; but do not damage the oil and the wine.”
"One of the four horsemen of the apocalypse. He rides on a black horse and holds a scale in his hands. He causes famine, starving people to death, but leaves the luxuries intact."
—Shin Megami Tensei III: Nocturne Compendium
Black Rider appears as one of the Candelabrum holders sent by Lucifer to test the Demi-fiend, possessing the Candelabrum of Wisdom. He first appears with the other Horsemen of the Apocalypse when the Demi-fiend first ventures into the Third Kalpa. After clearing the Obelisk (but only after defeating White Rider and Red Rider first), Black Rider will appear inside an empty room on the second floor of the Shinjuku Medical Center's Annex Building. Defeating Black Rider in battle will get the player the Candelabrum of Wisdom.
After being defeated and once the player reaches level 61, Black Rider can be fused in the Cathedral of Shadows on the New Kagutsuchi phase if the player possesses a Deathstone, a special item found only in the Labyrinth of Amala. Black Rider can be fused by any combination of demons resulting in a Night race.
Black Rider appears as the summon orb boss of the Suginami Tunnels silver-level instance. He also appears as a boss within the Chain of Curse Deep Docks instance and a boss of the TR-Route of Denshi Kairo, through which the ability to fuse him can be obtained. He is a special triple fusion of Red Rider, Legion, and Jikokuten.
Black Rider has a 1/256 chance of appearing in the Tennozu Shelter, at the small vent near the center of the shelter. His Almighty-spam mode is set by Ice resistance. The reward for defeating him is 300,000 macca, 3 Gold Death Masks, and the ability to create him in special fusion.
Black Rider is fought alongside the other three in the Challenge Quest, Errand for the Apocalypse. Belial has sealed the four in a Domain found in Infernal Tokyo's Ikebukuro. They are far weaker than they are when encountered normally, that does not make them any less threatening. If Flynn makes any attempt to challenge them before accepting the quest, the Fiends will eject him from the domain. Completing the quest grants Flynn the Peacemaker, which is only surpassed by the plasma gun in terms of raw power.
Black Rider, along with all the other Fiends, is encountered in Twisted Tokyo. Black Rider is encountered on B9F and drops the Constraint Scale second cycles onwards. He is fought at level 958 on cycle nine.