Aqua trying his best to be an edgelord only to find out that Akane is committed 110%. It really caught him off guard. Also, I love the way they brought this scene to life. With the emphasis this show puts on eye animation, it was a nice touch to actually darken Akane's eyes when she went full Darth Akane.
I'm sure they're both good actors, even with different approaches to the craft, but Kana has the baggage of being famous as a child actor, kind of like Ron Howard, but he's doing fine.