As I'm sure some of you know, when White plays 1. a3, 1... e5 is typically Black's top response. If this happens, the top move to still keep the game classified as an Anderssen Opening game is 2. e3. Since this opening doesn't have an official name, aside from just plain "Anderssen Opening", I've decided to name it, the Japanese Opening. Why that? Well, Japan has yet to have an opening named after it, the pawn structure loosely resembles the shape of Japan, and most importantly, it's a solid opening. Alternatively, this opening set-up could also be attained by playing 1. e3 e5 2. a3, however, playing 1. a3 is a better way to ensure 1... e5 as that is the top engine move response as well as a natural opening move.
After 2. e3, Black's top two responses are either 2... d5 or 2... Nf6. If Black goes 2... d5, the best response is 3. d4, turning the opening into a Japanese Opening: Normal Variation.
If Black decides to play 3... Nc6, White plays 4. Nf3, enticing Black to play 4... e4. If they don't, White will gain the advantage, though how much depends on Black's move. But if Black does play 4... e4, White must play 5. Nfd2, and by doing so, enters the Tokyo Variation of the Japanese Opening.
At this point, the eval bar is at -0.20, however Black needs to play perfectly as any misstep could cost them. Though in terms of White's next move, it will almost always be 6. c4 regardless of Black's 5th move.
Here's an example game against the Nora bot (with assisted mode on for learning purposes)
As you saw, one false move easily turned the tables.