Yokozawa Shōgen (横沢将監) was a Japanese samurai of the sixteenth century, who served Date Masamune, ruler of the Sendai domain.
He remitted a letter and some merchandise from Date Masamune, and was baptized, receiving the name of Don Alonzo Hacaldo.
The ship sailed in April 1618 for a fourth trans-Pacific travel, and arrived in the Philippines, where she was bought by the local Spanish government in order to "reinforce defenses against Holland forces by all means possible".
After his arrival in Japan, Yokozawa is recorded to have renounced the Christian faith and burnt all his Christian-related belongings.
In 1621 however, Yokozawa Shogen is known to have signed a letter to the Pope together with seventeen other Christians from Northern Japan.