You need an embassy visa for Northern Mariana Islands if you have a Brazilian passport
Visa options for Northern Mariana Islands
Visitor visa
To visit the Northern Mariana Islands for Business or Tourism, you require a visa. A paper or embassy visa is the only type of visa available for visitors. Typically the visa is a stamp or sticker added to your passport. You must submit your application through the consulate or local visa center. Visit the government website for details.