コトコト

コトコト

with a rattling sound; with a (gentle) clinking sound; rapping (on a door)

N3Adverb
Adverb, Adverb (to particle)
with a rattling soundwith a (gentle) clinking soundrapping (on a door)
Adverb, Adverb (to particle)
(cooking) at a simmer(boiling) gently(bubbling) lightly