Joaquim Konishi, born as Ryuusa Konishi, is a Christian Samurai and head of a powerful merchant family in Sakai. He and his clan aided the Oda Faction during the Battle at Kiyomizu Temple and joined Nobuna Oda's alliance due to her religious tolerance and the rescue of Louise Frois, a leading Christian in Japan, by Nobuna's retainers.
Joaquim Konishi is the oldest son of a wealthy Sakai merchant and inherited the position and wealth of his father after his death.
Living in free city of Sakai, center of the Christian religion in central Japan, he early came in contact with Christianity and finally converted, being baptized by Louise Frois as Joaquim Konishi. At first, he did so because he gained advantages in trade with foreigners by converting. However, under Louise's influence he later became a faithful Christian while his wife Maria Konishi and his daughter Augustine "Yukinaga" Konishi converted as well.
Even though Joaquim was successful as merchant, it was his military aide for the Christian purpose and other converters that made him a local celebrity. He created his own private army of Christian Samurai and Ashigaru, financed by his extensive fortune.
Nevertheless he never became one of leading merchants of Sakai, probably due to his belief.
After the coup of the Miyoshi Three and the following occupation and destruction of Kyoto, Louise was rescued by Nobuna Oda's retainers Yoshiharu Sagara, Inuchiyo Maeda, Goemon Hachisuka, and Hanbei Takenaka from bandits. Convinced by Yoshiharu that Nobuna Oda would be the one to save Japan and end the wars, she allied herself with the Oda Faction. The capital was eventually liberated from the Miyoshi Three and secured by the Oda Faction, ending the reign of terror within the city.
However, the Miyoshi Three counterattacked and besieged Kiyomizu Temple, in order to kill the Imagawa Shogun who was allied to the Oda and drive Nobuna's army out of Kyoto. This attack was led by Hisahide Matsunaga, the feared "witch of the civil wars". The desperate Oda Daiymo without any troops within reach sent a message to Louise and asked her for help. The nun agreed and gathered all Christians around Kyoto, notably Joaquim Konishi and the Daiymo of Takatsuki, Dom Justo Takayama. Together with a army of free Christian Ashigaru under Louise's leadership, Konishi's and Takayama's troops entered Kyoto and defeated the army of the Miyoshi Three, rescuing Nobuna and forcing Hisahide Matsunaga to surrender.