If you played Dynasty Warriors I no need to tell anything, but if not, here it goes!
Guan Yu was a general from the late Han dynasty and the period of Three Kingdoms, for his deeds in battle, honor and loyality he is reverd in China as the good o war! He served Liu Biu, an scion of Han dynasty, hoping to restore the old rule, acording to Romance of Three Kingdom he was sworn brother with Liu Bei and Zhang Fey.