Siena Oji, a four-year-old mare from Japan, is trained by Hiroyuki Yamaguchi. Bred by Belshazzar and Taiki Elise, Siena Oji has yet to win a race in her 17 starts. In her most recent outing at Himeji on January 24, 2024, Siena Oji, ridden by Kazuma Okaki, finished eighth behind Meisho Rolls.