The artist often addresses the changing nature of natural phenomena in his works: waxing and waning, shifting shadows, changing seasons.  Yufudukuyo is a seasonal word for the moon, and can be translated more specifically as the waxing moon.

“Yufudukuyo” appears in a poem by Princess Shikishi (1149-1201):

色つぼむ梅の木の間の夕月夜春の光をみせそむるかな

iro tubomu -  In between

mume (ume) no ko (ki)no ma no -  The plum trees sprouting in color

yufudukuyo (yuzukiyo)  -  It is the evening moon

faru (haru) no fikari (hikari) wo -  That hues revealing

misesomuru kana -  The light of spring