訓 ほたる ・ 音 ケイ
漢越音: huỳnh
Insect 虫 with glowing flames on top: the bug that lights up. Sino-Vietnamese huỳnh as in huỳnh quang (fluorescent, 蛍光).
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
夏の夜に蛍が飛んでいた。 (なつのよるにほたるがとんでいた)
Fireflies were flying on the summer night.