Konosuke Oshita, known as Gansley in English, is the leader and founder of the Big Five and an antagonist in Yu-Gi-Oh!.
He was voiced by Nobuyuki Saitou in Japanese and Marc Thompson in English.
Oshita's business career began with a lemonade stand that he stole from his neighbor. He soon became the biggest lemonade distributor, and then started working for Gozaburo Kaiba at Kaiba Corp. With the other four members of the Big Five, Oshita conspired with Kaiba to take over Kaiba Corp and overthrow Gozaburo. Their plan succeeded but Kaiba betrayed them so when Pegasus J. Crawford attempted to take over Kaiba Corp, the Big Five joined forces with him to help him. After Pegasus was defeated by Yugi in a duel, Kaiba fired the Big Five, but they trapped him in his own virtual world and attempted to sacrifice him to the lava pit to awaken the Five God Dragon. When Yugi Muto, Katsuya Jonouchi, Mai Kujuaku and Mokuba Kaiba entered the game, the Big Five summoned the Five God Dragon themselves. Oshita appeared to control its center head and killed Jonouchi, Mai and Mokuba (from which they were later revived), but when Yugi and Seto combined their monsters to destroy the Five God Dragon, the Big Five were imprisoned in the virtual world.
They were there so long their bodies were destroyed til they found Noah Kaiba and entered his virtual world. They agreed to defeat Yugi, Seto Kaiba and the others as they needed to steal their bodies to escape.
Oshita took the form of Deepsea Warrior and dueled Yugi. His deck is water themed, and he was able to sacrifice two monsters to create a barrier to reflect any of Yugi's attacks back at him. However, with Kuriboh as his deck master (though Yugi intended to choose the Black Magician), he was able to attack Oshita directly and defeat him.
Oshita was digitized, but not destroyed. He later returned alongside his defeated comrades Shuzo Otaki, Chikuzen Oka and Kogoro Daimon, attempting to steal the bodies of Jonouchi, Shizuka Kawai and Ryuji Otogi. Oshita broke up a fight between Otaki and Daimon before Noah recalled them, as they had not won the bodies in a duel.
Eventually they all entered Hiroto Honda's body, which had been stolen by Soichiro Ota. They dueled together against Yugi and Jonouchi, rotating around. He was only dueling for one turn before Otaki took over. Yugi and Jonouchi defeated the Big Five. They attempted to steal the gang's bodies again but Noah sent them back to his room. They begged him for another chance but he gave them no more chances and deleted/killed them.
In the 4Kids English dub, Noah imprisoned them each in a different corner of the virtual world. Oshita was killed along with Noah, Gozaburo and the other members of the Big Five when Noah caused a satellite attack that destroyed the fortress that the virtual world was stationed in, deleting the virtual world and anyone in it.
As a businessman, Oshita knows many business strategies but is quite unethical in his business career as he would fire his workers for no reason and began his business career by stealing a lemonade stand from his neighbor. He also seems to be one of the better duelists of the Big Five, as he came close to defeating Yugi, apparently having analyzed every aspect of the duel but underestimated Kuriboh which led to his downfall.