Buddha. Ancestral spirit. A term written with the character used for butsu (the Buddha) but generally meaning the souls of ancestors who after a period of time and the proper rituals 'become buddha' (hotoke ni naru 'to become Buddha' is a polite term for dying). Hotoke are either ancestors of one's family or muen-botoke ('unrelated ghosts'). In either case appropriate memorial rituals are required in order to pacify the spirits and avoid the possibility that by neglect a spirit may become an onryo or angry ghost of the kind epitomised by Sugawara, Michizane. Since hotoke beliefs (i.e. ancestor rites) are common to virtually every religion in Japan even 'pure' Shinto funerals such as those developed after the Meiji period have to incorporate memorial rites for a proper period.
See Sosai.
A Popular Dictionary of Shinto. Brian Bocking.