He is making a futile effort like trying to scoop up the moon from the bottom of the sea.

He continues to chase a dream like chasing the moon in the sea.

He is so engrossed in his work, it's like 'Wu's cow gasping at the moon'.

He reacts excessively to even small problems, like the proverb 'Kureushi Tsuki ni Aegu' which means 'excessive fear'.

He is always facing difficulties, just like the proverb 'clouds over the moon, wind in the flowers'.