Artemisia princeps, the Japanese mugwort, a perennial plant species found in Japan
The larva is reddish brown with black markings and usually feeds on the foliage of mugwort, although it has also been recorded feeding on Angelica, bilberry, tansy and yarrow.
As the name suggests, the larva feeds on the flowers of mugwort (which is sometimes called "Common Wormwood") but will also feed on the flowers of a range of other plants (see list below).