Kohtaro Minami (南 光太郎 Minami Kōtarō) is the original Kohtaro Minami's secondary incarnation from Kamen Rider Decade.
Kohtaro was born on the day of a solar eclipse, along with his stepbrother Nobuhiko Akizuki, within the same hospital. Golgom noticed this, and both brothers were entitled heirs to their leader, the Creation King's throne. After Kohtaro's parents both died (when Kohtaro was around 3 years old) as a result of an apparent accident, Prof. Akizuki then adopted Kohtaro alongside Nobuhiko as if they were brothers. On the night of their 19th birthday, they were captured by Golgom and were remade into cyborgs and infused with King Stones. Kohtaro received the "Stone of the Sun" to become Century King Black Sun (世紀王ブラックサン Seikiō Burakku San). However before the final brainwashing Soichiro Akizuki interrupted the final stage of the process with Kohtaro barely escaping.
Having been pursued by Golgom after his escape, Kohtaro discovers his newfound ability to turn into the a grasshopper humanoid as a result of their surgery, along with his newfound super strength and cyborg abilities.
After receiving a letter from Soichiro, Kohtaro secretly meets with his foster father and learns the truth about his childhood. Soichiro reveals to Kohtaro that he agreed to join Golgom in order to receive funding for his archaeological research in exchange for Kohtaro and Nobuhiko to be operated on during their 19th birthdays. When Kohtaro's father had refused to join the organization, Golgom had him and Kohtaro's mother assassinated. After Prof. Akizuki is killed by five of Golgom's Spider Mutants, Kohtaro transforms once again and takes the title of "Kamen Rider Black." He then vows vengeance against Golgom and seeks to rescue Nobuhiko from their clutches. As Black, Kohtaro gains support from Nobuhiko's younger sister, Kyoko, as well as Nobuhiko's girlfriend Katsumi. He would often be found working part-time with the two girls at the Capitola café. He would also gain allies in fight against Golgom, such as Interpol officer Ryusuke Taki and Golgom's own Whale Mutant.
Eventually Kohtaro reunites with Nobuhiko; however, Nobuhiko was converted into the perfected Century King, Shadow Moon. In their fight, just when Kohtaro was winning the fight, the Creation King temporarily turned Nobuhiko back into human form again. This caused Kohtaro to lose the fight as Nobuhiko turned back into Shadow Moon and launched a surprise attack. He then tried to convince Shadow Moon that Earth belongs to all living things and was landed a finishing blow. As he turned back into human form thus causing Shadow Moon to hesitate and decide against taking Kohtaro's King Stone, Kohtaro was killed and his family had to evacuate from Golgom's reign over Japan. Eventually Black was resurrected and fought his way through hordes of monsters until fighting Shadow Moon and unwillingly defeating him. Kohtaro was then mercilessly taunted by Shadow Moon who told him that he shall feel regret for the rest of his life knowing that he killed his best friend and step-brother Nobuhiko. Despite these cruel words, Kohtaro told Shadow Moon to stay alive so they can later escape together.
Using the Satan Sabre used by Shadow Moon, Black then fought against the Creation King of Golgom and destroyed him. The base soon started to self destruct which prevented him from getting Shadow Moon out to safety. Kohtaro then looked at the ruins while saying Nobuhiko's name. With the Golgom defeated, Kohtaro visited the Capitola bar before leaving for unknown parts.
Unlike his counterpart in the World of Black RX, he is warned of Decade and initially sees him as an enemy. It is not until the interference of Dai-Shocker does he finally consider Decade as an ally, revealing that he has been fighting Dai-Shocker with the aid of Joe the Haze.
When Tsukasa makes it back to World of Black RX, DiEnd uses his Kamen Rider Black card to summon this Kohtaro (in person, and not as a manifestation). Kohtaro and his counterpart battle side by side.
In Kamen Rider Decade: All Riders vs. Dai-Shocker, unlike most other A.R. World riders, this A.R. World version of Kohtaro had an active appearance, fighting as Kamen Rider Black, while the original Kohtaro Minami appeared as Kamen Rider Black RX. Joining the Rider tournament that was supposed to stop the fusion of worlds, he made it to the finals, fighting alongside Kamen Rider Super-1 and Kamen Rider V3. They're defeated by Decade and are taken for dead after disappearing in a dimensional wall. However, the Riders were just regrouping while waiting to mount an offensive against Dai-Shocker, and they all reappeared to help Kamen Rider Decade when he attempted to face Dai-Shocker's troops alone.
Although this version of Kohtaro Minami and his A.R. World aren't specifically referenced after Decade, from the point of the introduction of this character, the concept of a Kohtaro Minami who never became Black RX existing alongside Black RX proper became a recurring part of the franchise. Many crossover movies started featuring Kamen Rider Black and Kamen Rider Black RX as independent, unique, individuals, without giving any specific explanations of their own for it, even while official material and even the movies themselves in some cases continue referencing both Riders as Kohtaro Minami.
Kohtaro would eventually reappear, fighting a mysterious Demon Lord for several hours, before killing it alongside FoxMask. Kohtaro has reappeared several times after this, usually fighting threats to mankind, or helping younger Riders with personal issues as senior Rider.
Some time later, he is targeted by the revitalized Golgom, who trick Kamen Rider Baron into fighting Kohtaro. During the battle, Kohtaro is able to explain his motives, as well as defending humanity's actions, effectively turning Baron against Golgom again. With this said, Kohtaro departs the battle on good terms with Baron.
Kohtaro is an emotional man which has served both good and bad for him. After seemingly losing his step-brother when he became Shadow Moon, Kohtaro tried very hard to get Nobuhiko back while being saddened at having to fight him. He also didn't truly give up on Nobuhiko and tried to save him even as Shadow Moon. Kohtaro had to eventually part with not only Battle Hopper who thanked him for everything, but also with Shadow Moon who he unwillingly defeated in combat serving as a maturity point for him. As saddened as he was for failing to save the both of them, Kohtaro chose to keep on living for himself showing strength for his character.
- Height: 197 cm
- Weight: 87 kg (191.8 pounds)
- Maximum Jump Height: 30m
- Punch: 15t
- Kick: 30.5t
This is the form that Kohtaro takes on when he activates his Kingstone, causing his body to grow dark armor, boosting his already considerable strength outside of this form.
- Rider Punch and Rider Kick: The primary killer moves in the entire series were the Rider Punch and Rider Kick which is charged with King Stone Energy at the right fist and the right foot. After delivering either one or both moves to any monsters, they would be engulfed in flames before finally destroyed. Kamen Rider Black discovered his weakness when he was fighting a Crab monster. His Rider Punch had no effect on the monster due to its strong shell. To increase his capabilities, Kamen Rider Black trained himself to find a new killer move to destroy the monster. While training, he discovered a new Rider Punch which was more effective and more deadly. These stronger variations of Rider Punch & Rider Kick gave out stronger force of light and were more blinding. The difference between the new and the old moves were that the new ones required Kamen Rider Black to touch his knees before hitting his enemies.
- Rider Chop: This move was very rarely executed and did not have enough power to destroy a monster.
- Multi-Eye: His eyes glow allowing him to see monsters' movements in the dark and detect their weaknesses, as well as allowing Kohtaro to not only see faster opponents, but adapt to their speed.
- Sensoring Ears: The triangular structures on both sides of his head would glow purple and enhance his hearing to super-human levels.
- Rider Sensor: Kamen Rider Black's antennaes would move to detect monsters which were moving too fast to be seen.
- Power Stripes: Black's striped bands on his neck and wrists would glow to repel any monsters' sticky fluids or goo on his body.
- Dragon Shoot: A move only seen in episode 16. The Dragon Shoot was taught by the Interpol Agent, Ryusuke Taki. Ryusuke threw the Ultra Quartz (a wanted object in the episode) towards Kamen Rider Black where he quickly jumped and kicked it with one foot.
- King Stone Flash: Perhaps the most powerful technique. By shouting out "King Stone Flash", Kamen Rider Black could fire a burst of energy from his belt. It worked every time to fend off the villains; whether it's the High Priests or even the powerful Shadow Moon.
- Kingstone: The King Stone(キングストーン|Kingu Sutōn) is Kohtaro Minami/Kamen Rider Black's means of transformation. Embedded upon the center of his belts is the artifact known as the Stone of the Sun (太陽の石|Taiyō no Seki).
- BATTLE HOPPER
- Length: 222 cm
- Height: 124 cm
- Weight: 118.2 kg (260.5 pounds)
- Speed: 500 km/h (310 mph)
- Power: 415
The Battle Hopper (バトルホッパー Batoru Hoppā) is a living motorcycle used by Kamen Rider BLACK. It was created by Gorgom, made specifically for the upcoming Creation Kings Black Sun and Shadow Moon. When Kohtaro Minami was ambushed by the members of Gorgom during his escape, he drives the Battle Hopper and finally got away from Gorgom headquarters. The Battle Hopper has the ability to heal its own wounds if damaged, and can stand on its own if knocked over. His special move is the Dynamic Smash, a body slam attack that is executed at full speed. Before the finale, because Battle Hopper is connected to the King Stones, it was controlled by Shadow Moon due to this connection until Black used his King Stone Flash to disconnect the two. After taking heavy damage and suicide ramming itself towards Shadow Moon, it thanked Kohtaro for everything and seemingly died.