Hypervitaminosis occurs when the intake of vitamins is too high.

He has prosopagnosia, which makes it very difficult to remember faces.

She was a secret kunoichi (female ninja).

He threw a handful of sand into the sea.

"Once in a lifetime" means to cherish the encounter that happens only once in one's lifetime.

He missed a once-in-a-lifetime opportunity.

He was focused on his work all day long.

One day, he suddenly decided to go on a journey.

No one knows what he did to spend one day.

This day was a very rare day for me.