You’re talking about Yasuke, and yes, he was a real African retainer of Oda Nobunaga. But saying he was practically the first foreigner given samurai status and calling that a form of citizenship is a stretch. Japan had other foreign born people involved in military/service roles, and samurai status in that period wasn’t the same as modern citizenship. Yasuke’s story is historically interesting though.
Sorry I do like my history to be correct on a football forum