Proto-Japanese: *sita-ta-
Meaning: 1 certainly, definitely 2 to acknowledge, admit, recognize, determine
Russian meaning: 1 точно, надежно 2 признавать, распознавать
Old Japanese: sitata 1
Middle Japanese: sitatam- 2
Comments: Cf. also OJ sita 'heart, mind' - if etymologically different from sita 'below' (which seems rather probable).