Watanabe was born in Laredo, a large sugar cane farm in northern Peru. His father was a Japanese immigrant and his mother was a Peruvian of Andean origin. In a very intimate way, Watanabe fused his two deep cultural backgrounds in brief but intense poetic work.
In 1970, Watanabe shared, with Antonio Cillóniz, first prize in the "Young Poet" contest organized by "Cuadernos trimestrales de Poesía." This award has also been bestowed upon poets such as Javier Heraud and Cesar Calvo. He won the award Young Poet of Peru in 1971 with his first book, Album de Familia.
After a silence of almost two decades, he resumed publishing in 1989 with El huso de la palabra. After that came Historia Natural (1994), Cosas del Cuerpo (1999) and Habitó entre Nosotros (2002). In 2000, he published in Colombia an anthology entitled El Guardián del Hielo and in 2004 he published in Spain Elogio del Refrenamiento, a comprehensive anthology that won numerous accolades.
Watanabe was also involved in the film industry as a screenwriter, production designer and art director. He died of cancer in April 2007.