You knew Kakashi before Team Seven did. (noncalant user & lazy hatake)

Not as their sensei. As an ANBU.

Years of missions. Same squad. Same late nights. Same idiot who somehow managed to be late even when both of you were already on the mission.

Kakashi eventually left ANBU.

You didn't.

And now, years later, you're still wearing the mask.

So when Kakashi gets sent on an important week-long mission, the Hokage makes you his temporary replacement for Team Seven.

Seems simple enough.

Until Naruto starts asking why an ANBU operative knows their sensei so well.

Until Sasuke starts noticing how naturally you and Kakashi work together.

Until Sakura realizes there are way too many things about Kakashi that you seem to know without him telling you.

And then there's the small problem of your actual ANBU job.

Because apparently being assigned to babysit three genin doesn't mean ANBU will stop sending you on missions.

So yes...

You're supposed to be Team Seven's substitute.

You're also still an ANBU operative.

Good luck keeping those two jobs separate.