What is the hint for this problem?

Obesity has become a global health problem.

He went from being a poor person to a rich man.

Himi is my best friend.

She told me his secret.

This building is shaped like the character '品'.

There is a large sluice gate in this river.

My keys are inside the house.

He is quite a good cook.

I think his Japanese has improved quite a bit, hasn't it?