I remember that same emotion when Chihiro shed a tear upon taking a bite of the onigiri. That feeling is actually difficult for me to describe. It's not sadness but there is an element of it. It's not regret, disappointment or agony of defeat. But it can contain a bit of each. That emotion is felt when all the traumas we've forgotten surge to your throat, and we try our best to keep them bottled up. The tears well up the more we try to suppress. And that's my relationship with onigiri. It is my "hotoke", spiritual protector, telling me all will be well. Just eat.