The midimu are the ancestral dead in their masked, dancing manifestation. A single masked figure is a lipiko (plural mapiko), embodied by a costumed dancer wearing a carved wooden helmet-mask tilted back on the head so that he sees out through its open mouth. The masquerade climaxes the boys' (and, in related forms, the girls') initiation, where the ancestors are understood to come back to rejoice at the initiates' passage into adulthood, making visible the bond between the living and the dead. The performance is bound up with secrecy and gendered exclusion: the mapiko are said to terrify women and the uninitiated, who must not learn the identity beneath the mask. Documented from Karl Weule's expedition of 1906 onward and made the subject of Paolo Israel's history of the genre, mapiko has continually reinvented itself across the twentieth century while remaining rooted in ancestral religion.