Nana Antwi Agyeibi was Kontihene in Denkyira Kingdom and chief of Denkyira Osabi. It happened that, Ntim Gyakari slept with his kontihene’s wife and wanted Nana Antwi Agyeibi to be killed.
Nana Antwi Agyeibi flew from Denkyira with almost two thousand followers which include his nephew Gyamfi When Ntim Gyakari heard that his kontihene and his followers has left his kingdom and they are heading towards Kwaman, he tasked his executioners to follow Nana Antwi Agyeibi and killed all of them.
These executioners and Nana Antwi Agyeibi and his followers fought at biposo and Nana Antwi Agyeibi won the fight with help of his nephew Gyamfi.Kumanini was added to Gyamfi for his braveness shown at that fight.
This is why Gyamfi is referred to as Kumanini. When Nana Antwi Agyeibi reached Kwaman (Kumasi), he was made Atwimahene and his nephew became otumfour Taahyenhene.It is Said, anytime Taahyenhene dies, it is Atwimahene who will bring one of his nephews to swear allegiance to Asantehene.