Japan - emperor, Russia - ?

TSAR
List of words for the clue Japan - emperor, Russia - ? from the crossword:
NERO OTHO OTTOI TITUS OTTO TSARS TRAJAN NEROS RULER OTTOIV OTTOII SHAH NAPOLEON KAISER CZAR IAN PEDRO OTHOI INCA
WordClue
YENRussia - ruble, Japan - ?
NERORoman emperor
EGYPTemperor - Japan, pharaoh - ?
INDIAemperor - Japan, maharaja - ?
JAPANtsar - Russia, emperor - ?
RUBLEJapan - yen, Russia - ?
RUSSIAemperor - Japan, tsar - ?
EMPERORRussia - tsar, Japan - ?
PENGUINAdelie or emperor
PHARAOHJapan - emperor, Egypt - ?
AUGUSTUSRoman emperor
AURELIUSMarcus, Roman emperor
CALIGULARoman emperor
CLAUDIUSRoman emperor
COMMODUSRoman emperor
MAHARAJAJapan - emperor, India - ?
TIBERIUSRoman emperor
CARACALLARoman emperor
VESPASIANRoman emperor
DIOCLETIANRoman emperor
MAHARAJAJapan - emperor, India - ?
KNIGHTJapan - samurai, Europe - ?