
Quick answer — Tomoko Nakamura voices Yaya Yuiki in Shugo Chara!, Himeko Tachibana in K-ON! Season 2, Midori Kunihiro in Shiki and 3 more characters.
Tomoko Nakamura voices Yaya Yuiki (Shugo Chara!), Himeko Tachibana (K-ON! Season 2), Midori Kunihiro (Shiki), Haruko Nitta (To Love Ru Darkness), Lace van Dracula Shikabane (Haganai), Eiko Morizono (Lord of Vermilion: The Crimson King).
Yaya Yuiki is voiced in Japanese by Tomoko Nakamura.