He is deeply studying about the 'U' in Buddhism.

There is a cat in my house.

Yu is my best friend.

I stayed up late every night and ended up ruining my health.

Kaya is my best friend.

He finished his work and went home at midnight.

He was working until late at night.

He is clearly a night owl, working late into the night and sleeping late into the morning.

An owlet moth is an insect that is active at night.

In Hinduism, Yama is considered the god who judges the souls of the dead.