Nanami Madobe

Nanami Madobe is the official OS-tan of Windows 7. She is the first official "OS-tan", in that she is marketed by Microsoft. 7777 Premium bundles of Windows 7 Ultimate DSP sold in Japan include a Madobe Nanami theme pack, complete with sound files and three wallpapers. Her name is a play on her voice actor's, Nana Mizuki, as well as Windows 7. The Kanji characters in her surname literally translate to "By the window", and her first name is also a play on "Nana", the Japanese word for 7. In Madobe Nanami no Windows 7 de PC Jisaku Ouen, she is computer store employee. Nanami has her own Twitter account. -Source: MyAnimeList