godan verb (-su), intransitive verb
burst into tears; start crying; be moved to tears
Describes the sudden onset of crying, often due to emotion or distress. Can be used for both literal crying and being deeply moved.
彼女はその知らせを聞いて泣き出した。
She burst into tears upon hearing the news.
感動して思
I was so moved that I couldn't help but start crying.