In Japan, there is even an onigiri anniversary. In recent years, there have been onigiri with fancier ingredients such as wiener onigiri and karaage onigiri, but onigiri can be made with simpler ingredients that are still delicious.
The English script for this episode can be found here. This will surely help you understand this entire episode. https://toralog.jp/podcast-episode77/
I introduce my hometown in English on YouTube. https://www.youtube.com/channel/UCJyb6vceAjGazPPGjJs-1Yw It has Japanese subtitles, so I think it'll be useful for your study! Please take a look at that as well!