灰
カイ, はい
ashes, puckery juice, cremate
JLPT2 G6 S6 F1717
The relevant seal inscription form combines 又# hand/action indicator and 火 fire → remove cinders by hand → *ash* → *gray*. Compare 煤. The present form replaces 又 with 厂 cliff/shape indicator, suggesting a cooking stove.
[Full Kanji Etymology List]