You know, those characters in anime or manga that provide convenient exposition that either clues viewers/readers in to the situation, or ask (forced) layman's questions that give an excuse for a nearby know-it-all character to give the lowdown.
And I'm her junior, Kotone!!Mob, you say?But she's even dressed like a mob character...Another mob character appeared from behind...Mo...This is no mob-character! This is the older sister of the battle legend Red -- Leaf! Eep! Yes? Whaaaaaaat?! For real!? Excuse me, little lady. Which way is the Battle Tree? You're pretty intense for some mob-character! So scary!Yes, older sister.