ドキドキ
dokidoki

To-Adverb

1. thump-thump; bang-bang; pit-a-pat; pitapat; pitter-patter

Onomatopoeia
かれ心臓 しんぞうがどきどき っているのを かんじた。
karewa shinzōga dokidoki utte iru nō kanjita.
He felt his heart beating fast.
Suru Verb

2. to beat fast (of one's heart); to throb; to pound; to palpitate

Onomatopoeia
Other forms: