Japanese Word for Sincerity
We use Japanese Kanji word “誠意(せいい-seii)” for translating English word “Sincerity” into Japanese. I showed large kanji image of this Japanese word in left side of this page.
And some other Japanese words also used for “Sincerity” such as “誠実(せいじつ-seijitsu)”, “真摯(しんし-shinshi)” and “真心(まごころ-magokoro)” etc.
And we have several other similar meaning words in Japan even though each of these words are often used slight differently.