World number 18 Hirano, who picked up her medal at London 2012, is favourite to take top honours at the event, where she will be joined by compatriots Shiho Matsudaira and Haruka Sakai - 74th and 88th in the world respectively.
The 29-year-old comes into this tournament having followed up her triumph at the Belarus Open with a last-32 exit in the Czech Republic, so will be keen to rediscover her form.
He Zhuojia and Fan Siqi lead the Chinese challenge, while Brazil's Gui Lin and Ana Godina of Argentina head South American hopes.
In the men's event, Argentina's Liu Song will be looking to add to his considerable list of achievements.
The China-born 42-year-old has been a regular medalist at the Latin American Table Tennis Championships since 1998 and has been installed as top seed for his home tournament.
A five-time singles winner of the event, Liu will certainly have his eyes on the prize in Buenos Aires.
His main competition will come in the form of compatriot and world number 256 Gaston Alto, who sits above a host of Chinese challengers in the seedings.
Liu Dingshuo, Zhu Cheng, Wang Chuqin and Xue Fei lead China's contingent in the men's draw.