2643. What character can be added to both of these characters to give other characters? 戸_ -> _旦

戸  KO, to - door

旦  TAN, DAN, akira, tadashi, asa - morning 

Add 月:戸+月 月+旦   

月  GETSU, GATSU, tsuki - moon, month

肩  KEN, kata - shoulder

胆  TAN - gallbladder, courage