
Quick answer — Sayori Ishizuka voices Luigi in Gosick, Masha in DRIFTERS, Izuru in Mermaid Melody: Pichi Pichi Pitch and 4 more characters.
Sayori Ishizuka voices Luigi (Gosick), Masha (DRIFTERS), Izuru (Mermaid Melody: Pichi Pichi Pitch), Shiina (Sekirei: Pure Engagement), You Susugihara (Asura Cryin' 2), Class Teacher (Karin: Chibi Vampire), Maya (Cat Planet Cuties).
Luigi is voiced in Japanese by Sayori Ishizuka.