Short answers, pulled from the story.
Oro is a fictional immortal hermit and martial arts master in Capcom's Street Fighter series. He first appeared in Street Fighter III: New Generation, depicted as an ancient fighter who deliberately restricts one arm behind his back to handicap himself in combat.
Oro restrains one arm as a form of self-handicapping, holding back his full power to make fights competitive. When he was brought back for Street Fighter V, the development team had him hold a tortoise named Yamasen in that arm to visualize the restraint in 3D.
The character design was overseen by Yuji Imamura, who had previously worked as a graphics designer on Capcom's Darkstalkers series. Producer Tomoshi Sadamoto supervised Oro's development directly, stating he formed an attachment to the character along the way.
Oro has decided that Ryu is the only martial artist worthy of inheriting his secrets. In his endings in Street Fighter III: New Generation and 2nd Impact, he selects Ryu as his intended successor. In Street Fighter III: 3rd Strike, he continues trying to make Ryu his disciple, though Ryu remains unaware of Oro's presence.
Contributing author Andre de Oliveira Matumoto, writing in the journal Tecendo Sentidos published by the University of Sao Paulo, argued that placing Oro's stage in Amazon caves while fellow Brazilian character Sean's stage was set in New York City presented a negative image of Brazil. He felt the contrast framed America as a place of aspiration and Brazil as an exoticized, hidden space suited to hermits.
Oro received mixed reception. Critics at Paste called him one of the strangest character designs in Street Fighter and appreciated the mystery around his fighting style. IGN's Rus McLaughlin cited him as an example of Street Fighter III's unusual new roster that alienated returning players. The Retronauts podcast said none of its hosts knew what to make of him, with some reporting they were creeped out by his appearance.