Semetua was Sem Manutahi, master of ceremonies and central figure of the "Tipaerui Valley" association. His role in the association was to find legends, and to set up traditional activities or ceremonies, in the upper valley of Tipaerui in the heart of the island of Tahiti. "This valley has a soul, a spirit that we always respect when we come. He said. It is animated by the spirit of the Mamaia. These people that we rarely met, that we feared and respected also, in the days of royalty. Some say they were healers, others say they were seers." Speaker on several occasions for troops at Heiva i Tahiti, master of ceremonies for the Tipaeui Valley association, Semetua has made his voice resonate on numerous occasions, to tell stories, protect a valley or quite simply defend his convictions.