You need an embassy visa for Northern Mariana Islands if you have a Brazilian passport
Visa options for Northern Mariana Islands
Visitor visa
Travellers need a visa to visit Northern Mariana Islands for Business or Tourism. A paper or embassy visa is the only visa available for travellers visiting Northern Mariana Islands. The visa is typically a stamp or sticker added to the passport. Travellers must obtain this visa from a local embassy, consulate or visa center before travelling.