Roughly half the surviving Noh repertoire is built on a single structure: a travelling monk arrives somewhere, meets a local person, and learns that the person is the ghost of someone who died there attached to a grief, a battle or a love. In the second half the ghost returns in true form and dances the memory out, and the monk's prayer releases the attachment. The plays are therefore a Buddhist argument staged as a dance: attachment holds the dead in place, and the release is the point.
Okina stands outside this and outside the category of drama altogether. It has almost no plot, its text is largely incomprehensible archaic syllables, and it is performed at New Year and at the opening of important programmes as a prayer for peace and a good harvest. The company purifies itself beforehand, the mask is carried onto the stage in a lacquered box and put on in front of the audience rather than in the mirror room, and the performer is understood to become a god while wearing it. Noh actors treat it as a rite that happens to be performed on a stage, and the distinction is theirs, not an outside classification.
The atlas records Noh honestly: it is theatre, it has been theatre for six hundred years, it is performed for paying audiences and taught in universities, and it retains inside it a piece that its own practitioners do not treat as theatre at all.