thorough knowledge of

know well, be familiar with, be well informed about

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend

distal demonstrative, something far off removed from both speaker and listener: that, yon / particularly, male personal third person pronoun: he / by extension from he: boyfriend

he; boyfriend

history / the study of history

Short for 日本国 (Nihon-koku): Japan (a country and archipelago in East Asia) / a surname

Japan

(archaic) Japan

everything