What's the (subtle) difference between "once again" and "yet again"? [closed]

I think they mean pretty much the same thing, but maybe the tone is different (or subtext)?

Example sentences:

Once again, I went to Shibuya, one of the busiest pedestrian intersections in Japan, and began a leisure afternoon of girlwatching.

Yet again, I went to Shibuya, one of the busiest pedestrian intersections in Japan, and began a leisure afternoon of girlwatching.

Solution 1:

They both technically mean the same thing.

I would say that the use of the word "yet" expresses an attitude of irritation or displeasure at the act of "girl-watching" again.

On the contrary the use of "once again" is neutral and doesn't express a positive or negative attitude.