Yotsoyba is the official mascot of 4chan(nel).org. Some newfags will pretend she is "sacred" which makes no sense whatsoever. Because of this, posting Yotsoyba gems and images of Yotsoyba being murdered, raped (Built for Big White Cock btw), or otherwise defiled/abused are a prime way to generate seethe among 4chuds.
She originally comes from a 4-koma manga Yotsuba&! which Moot was a big fan of.