A Franciscan friar named Luis Sotelo, who was proselytizing in the area of what is now modern Tokyo, convinced Tokugawa Ieyasu and his son Tokugawa Hidetada to send him as a representative to New Spain (Mexico) on one of their ships, in order to advance the trade treaty. Rodrigo de Vivero offered to sail on the Japanese ship in order to guarantee the safety of their reception in New Spain, but insisted that another Franciscan, named Alonso Muños, be sent instead as the "shōgun" representative. In 1610, Rodrigo de Vivero, several Spanish sailors, the Franciscan father, and 22 Japanese representatives led by the trader Tanaka Shōsuke sailed to Mexico aboard the "San Buenaventura", a ship built by the English navigator William Adams for the "shōgun". Once in New Spain, Alonso Muños met with the Viceroy Luis de Velasco, who agreed to send an ambassador to Japan in the person of the famous explorer Sebastián Vizcaíno with the added mission of exploring the "Gold and silver islands" ("") that were thought to be east of the Japanese isles.