The Manvantaras & Dissolution of the Universe - Verse 57-58

The other Vaivasvata Manu was the son of Savarna (i.e. Chaya, the shadow of Samjfia) . The four Savarna Manus born of the great sages will be equipping themselves with ( the power of) penance. They will achieve all their tasks in their respective future Manvantaras.