Complex sentence: She was trapped by Kagato and later released by Mihoshi, it is revealed in OVA 3 and some spinoff media (and hinted in OVA 2) that Washu is a human manifestation of a sister-goddess to Tsunami and Tokimi.
Split into simpler sentences: She was trapped by Kagato and later released by Mihoshi. It is revealed in OVA 3 that Washu is a human manifestation of a sister-goddess to Tsunami and Tokimi.