2186. What character can be added to both of these characters to give other characters? 北_ -> _方

北  HOKU, kita - north

方  HOU, kata - direction

Add 月:北+月 月+方  

月  GETSU, GATSU, tsuki - moon, month

背  HAI, se, somu(ku), somu(keru) - back, height, act contrary to, avert

肪  BOU - animal fat