Saber-class Servant from Fate/extra.
While she bears a striking resemblance to Saber of Fate/Stay Night with blonde hair and ahoge, and green eyes (although of a different hue), she is also noticeably more well-endowed. Her personality is more outgoing and haughty, albeit engendered by a sense of noblesse oblige.
Her preferred outfit is a red dress with epaulettes and a see-through part that shows a white leotard underneath. Sometimes depicted with her sword, Aestus Estus. Her Noble Phantasm is Aestus Domus Aurea, a giant colosseum. Also gains an alternate costume for Fate/Grand Order's 2017 Nero Festival, consisting of a gym uniform (a white shirt with a name tag and buruma), a red headband, socks and sneakers.
Unlike Saber Alter or Saber Lily, she is a separate character from Saber, so the Saber tag should not be used for images containing Saber Extra unless both characters are shown together.