He is an intersex person, possessing both male and female gender characteristics.

He completed the project in a week.

I'm always busy during the daytime, and I only have time to rest at night.

He had been working overseas for an extended period of time.

The theory of spacetime is an important part of physics.

Mr. Mashiwa is my best friend.

Sakakima is my best friend.

Mr. Azama is my best friend.

He was a bit dimwitted, so I had to repeat the explanation several times.

I really think he's a dimwit.