The article explores translation processes behind diplomatic negotiations between Japan and the Spanish overseas empire in the sixteenth and seventeenth century. It applies a multi-layered approach that integrates the translations of original diplomatic documents with their re-translation as historiographical source compilations in the nineteenth and twentieth century. Analyzing the different connotations and nuances of friendship as a diplomatic concept, it highlights the impact of translation, both linguistic and cultural, as well as the strategies behind terminological choices, on intercultural encounters.