Tu is the God of War. He is Maui's father. Tu appears in MAUI, and MAUI 2: Tane is Lost. He is more kindly than his Maori Mythological counterpart, although he looks fearsome. He has a kindly old voice, as if he is a wise but kind old man.
In some myths, Maui is in fact the son of the Guardian of the Underworld, Makeatutara.