Marina the Monk was born a woman but chose to live as a man (changing her name to Marino) for the immediate purpose of joining her father in the Christian monastic life, perhaps originally in the caves of the Qadisha Valley in Lebanon, although her legend has been localized all across the Christian world. In Japan, too, her legend appears in the Barreto Manuscript in the Vatican Library, though not in the printed collection Sanctos no gosagueo of 1591, and it is one of only four saints’ lives extant in Japanese-script hand copies confiscated from hidden Christians during the Edo period. In the story, Marino is accused of having fathered an illegitimate child in the surrounding community, and rather than reveal his secret he accepts the blame, is expelled from the monastery, and dies alone in poverty, and when his estranged colleagues go to wash his body they realize he was innocent and bury him with great honors. I do a close reading of the two extant Japanese versions together with the Portuguese source, highlighting the process of stylistic localization and the theme of unjust condemnation and the burden of a secret, which the hidden Christians evidently found so compelling.