Soichiro Ota, known as Nesbitt in English, is one of the Big Five and an antagonist in Yu-Gi-Oh!. He's the technical expert of the Big Five and arguably the most significant of them, as he is the only one who succeeds in stealing a body. He is also described by some as being a nerd.
He was voiced by Hiromi Sugino in Japanese and David Wills in English.
Soichiro Ota owned his own lab where he built war machines that he built for his boss, Gozaburo Kaiba. When Seto Kaiba took over (in which the Big Five joined forces with him), he burned down Nesbitt's lab, as Seto wanted to make games at Kaiba Corp rather than machines for war.
After they joined forces with Pegasus J. Crawford to take over Kaiba Corp and Pegasus was defeated by Yugi Muto, Seto fired the Big Five, but they trapped him in a virtual world. Nesbitt controlled the fire head, but when their Five God Dragon was destroyed, they were imprisoned in the virtual world instead.
Their bodies were destroyed eventually but they soon found Noah Kaiba in his virtual world, and worked for him to steal the bodies of Yugi and the gang. Taking the form of Machine Sergeant (Robotic Knight in the English dub), Ota targeted Shizuka Kawai, who was with Hiroto Honda and Ryuji Otogi, but eventually decided on dueling the three of them at once, though he seemed intent at defeating Shizuka first (likely because she has never dueled before, despite Tristan's lack of experience). Despite the fact that it was three-on-one, with Honda and Shizuka as the least experienced of the four, Ota gained the advantage. He destroyed Honda's deck master while aiming for Shizuka's monster, sending Honda falling into a molten pit, trapping his mind in a robot monkey and holding his body in a virtual chamber.
Ota entered the field himself during the duel, and immediately fused with Machine King into Perfect Machine King. He was defeated when he and Shizuka's fusion monster, Saint Jeanne, destroyed each other, but he won Honda's body and after a confrontation with Kaiba and Honda, kidnapped Mokuba Kaiba, who was then taken from him by Noah.
Afterward, Konosuke Oshita, Shuzo Otaki, Chikuzen Oka and Kogoro Daimon entered Honda's body and all five of them dueled Yugi and Katsuya Jonouchi at once. Otaki took over for one turn but fell victim to Yugi's trap after which Daimon took over. After the Big Five were defeated, Noah imprisoned them each in a different corner of the virtual world.
Nesbitt was killed along with Noah, Gozaburo and the other members of the Big Five when Noah used a satellite attack to destroy the fortress that the virtual world was stationed in, deleting it and everyone inside it. He was later seen in season 4 flashbacks when Alister mentions Kaiba's stepfather kidnapping his parents and brother though whether Nesbitt was real or another illusion is in question with Dartz revealing he kidnapped Alister's parents and brother disguised as Gozaburo.
Ota is obsessed with robots. While in the form of a robot in the virtual world, he would often talk like one, using terms such as "negative" and "disassemble" and referring to Shizuka only as "the female".
- Initially, Ota stood out the least of the Big Five, being mostly out of sight once they were no longer shadowed and having only two lines in Season one and none in Season three up until his duel with Honda, Shizuka and Otogi. Ironically, Ota played the biggest role as he was the only one who was successful in stealing a body, though this excluded him from when the other four chased Jonouchi, Shizuka and Otogi.
- In Season four, Ota is seen is flashbacks with Gozaburo, which means this may have just been another illusion.