On a recent spectacular spring day, I took a walk from Tokyo’s Shibuya to the hip district of Shimokitazawa. It was one of the year’s first days of T-shirt weather and the cherry blossoms were blooming.

But by the time I arrived, my eyes were itchy and watering, my throat scratchy and I began hacking and sneezing. There was only one possible cause, I figured: After more than two decades in Japan, it was time for my "debut.”

Hay fever is such a pervasive and increasing problem that this is how people often describe the sudden onset of pollen allergy. "I’ve debuted this season,” they will say when they are beset by the cold-like symptoms after years of sniffle-free springs.