Kudan

In Japanese folklore the kudan is a yokai with the body of cow and the head of a human. It is born from a cow, but has the ability to speak human language. The kudan's birth is believed to be an omen of a significant event. Soon after they are born they give one or more prophecies and then immediately die, or they die once thier prediction comes true, which it always does. 

'The Kudan of Kurahashi Mountain' - tile engraving, ca. 1836.

Despite many kudan prophecies being about negative events, pictures of the kudan are believed to be good luck charms and they are often carried as talismans. This may be due to their perceived honesty considering their predictions always come true.

lylecore via deviant art

Shigeru Mizuki from GeGeGe no Kitaro