Yuuyu (ゆうゆ, Yūyu, born January 1) is the artist name of Yūna Sasara (篠螺 悠那, Sasara Yūna), a Japanese music producer, mainly of Vocaloid songs, from Aichi Prefecture. He is member of the music unit smileY inc. alongside with voice actress Yuka Otsubo (大坪由佳).