Itasha (痛車) is a Japanese term for an otaku(fan boy) fad of individuals decorating the bodies of their cars with fictional characters of anime, manga, or video games (especially bishōjo game or eroge). These characters are predominately "cute" female. The decorations usually involve paint schemes and stickers.
In 1980s, when Japan was at the zenith of its economic might, Tokyo’s streets were a parade of luxury import cars. Among them, the 'itasha' - originally Japanese slang meaning an imported Italian car - was the most desired. However, in 1990s, the term 'itai' was adopted to describe intense, cultish otaku associated with serial killer Miyazaki Tsutomu. Since then, Itasha (as the decorated vehicle) was derived from combining the Japanese words for itai (痛い, painful) and sha (車, vehicle). Itai here means "painful", which can be interpreted as "painfully embarrassing" or "painful for the wallet" due to the high costs involved.
Check out the Japanese Itasha convention here!
http://www.moeyo.com/2009/10/ita-g_2009_sokuhou.htmlAnd model kit selection here:
http://www.1999.co.jp/search_e.asp?Typ1_c=101&scope=0&scope2=0&urikire=1&itkey=itasha