He is studying about the history of black people.

He is known as a solitary genius.

He is deeply involved in national affairs.

He was staring into the empty space.

He felt a sharp pain in his groin.

He felt a sharp pain in his crotch.

In my house, we cook fresh rice every day.

Japan pursued a policy of national isolation for a long time during the Edo period.

Japan in the Edo period closed the country to foreigners.

He was invited as a state guest of our country.