noun
beat reporter; assigned reporter
A journalist assigned to cover a specific person, organization, or field, often to obtain exclusive or up-to-date information. Common in political and sports journalism.
首相の番記者は毎日官邸に詰めている。
The prime minister's beat reporter is stationed at the official residence every day.
彼はプロ野球チームの番記者として記事を書いている。
He writes articles as a beat reporter for a professional baseball team.
担当記者 is a broader term for a reporter in charge of a certain area or topic; 番記者 emphasizes the close, often exclusive, assignment to a specific individual or organization.
Compound of 番 (ban, 'watch' or 'duty') and 記者 (kisha, 'reporter'). The term likely originated in journalism to describe reporters assigned to monitor a specific person or beat.