Japan has four season as Spring, Summer, Autumn, Winter, plus one more Rain season as "Tsuyu". Usually it starts from June to middle of July. Humidity is very high during "Tsuyu" and it is un-comfortable for us.
However rain is very important for agriculture and also pearl farm before summer.
Pearl oyster need good plankton for feeding. Good plankton come from forest in mountain and rain bring them to the sea.
It has been not much rain during "Tsuyu" in Japan in recent years. It is problem for pearl farming.
So pearl farming is relied on nature and we have to take care more about nature.