陛
ヘイ
highness, steps (of throne)
JLPT1 G6 S10 F1429
坒# is 比 line up + 土 earth → neatly aligned earthen steps. 陛 adds 阜 piled earth → *steps* (of an imperial throne) → *imperial*. 陛 was devised to replace 坒 (a character not used independently in Japanese).
[Full Kanji Etymology List]