(Telecompaper) Over 83.8 percent of Japan's mobile phone customer base are customer using smartphones, which represents an increase of 6.9 percent year-on-year. The remaining 16.3 percent are feature phone users, according to a report from the Communications and Information network Association of Japan (CIAJ). Smartphone use among respondents in their teens, twenties and thirties was nearly or had reached 100 percent, the report also shows.