One of Typical Spring Flavor....
These are called Kogomi.
I always enjoy seasonal food.... because they have the maximum nutrition that your body needs.... so, one is for health reason... another is... to fully enjoy the season....
Let me quote a paragraph from Japan Times ( "The Unmistakable Taste of a New Season ")
" While some sansai are cultivated these days, connoisseurs prefer the stronger bitterness of sansai gathered in the wild. Sansai went out of vogue for a while, but with the recent interest in health and "natural living" they've made a big comeback. Their bitter, even tannic quality is believed to have a salutary effect on the body, especially after a winter of stodgy food. According to folklore, bears waking up after their winter hibernation nibble on sansai to get their digestive systems going. Most sansai are also rich in vitamins and minerals as well as fiber. "