READING  カイ、はい
MEANING  ashes
JLPT level N2 (full info & stroke order)
You can see this character as something got stuck on the flame. The first word in the list below (灰汁) has an exceptional reading, but it is a word you surprisingly come across often.
 
Words/compounds
あく
lye, harsh taste, scum (formed when cooking some foods), (excessive) strength of will
はいざら
ashtray
はいいろ
grey, gray, ashen
 
Example sentences
灰汁
煮え立たせる寸前で弱火にして、もう一度灰汁を取り除きます。
Just before bringing it to the boil, set to a low flame and remove the scum again.
灰皿
彼は灰皿を拾い上げた。
He picked up the ash-tray.
 
Lookalikes
 
タン、すみ 
charcoal