Yuki and Kiyoteru were designed to be VOCALOIDs that had human-esque traits about them. Yuki is designed to sing childrens songs and has an innocent, soft and cute voice. However, she was not voiced by a professional child singer and does not produce professional singer results. She is still a faithful CV vocal, and gives an accurate portrayal of a child voice.
Vocal traits as noted:
Her child-like voice makes her unique among the VOCALOID 2 voicebanks and allows for a soft, sweet style of song without being too "Loli" sounding.
She was the youngest sounding vocal released during the VOCALOID 2 era and is only "child" vocal in VOCALOID2 voiced by a child.
Her voice is very soft, leading to her higher notes losing some clarity compared to her lower notes but it gives her voice has a realistic and natural tone.
Due to not being from a professional singer, her voice has no ascension and lacks power. Expression is difficult and the voice is more limited in its roles for music.
Ten years after Yuki's release, her voice provider confirmed that she was recovering from influenza at the time of recording which likely attributes to Yuki's "huskiness".
Phonetic notes as noted:
She has strong consonants. Some users say the beginning consonant sounds get shorter as well as with other AH-S vocaloids.