Thread:NightFalcon9004/@comment-23771723-20160120054059/@comment-23771723-20160120155758

That's the one! Thanks for that.

The rule about using the present tense is known as Literary Present Tense. There are resources online, but just to grab a few: this grammar page, this writing page, this worksheet, and Wikipedia has a section on fiction under it's Historical Present page. Essentially, events in fiction exist in an "eternal present" and are always happening now, so they're discussed in present tense. Since Naomi is actively an FBI agent during the novel, then when discussing her FBI status, she's presently an FBI agent, so present tense is used. If the novel didn't exist and it were just the manga, then past tense would be used, since she was only an FBI agent in the past, before being depicted in the story.