(pronounced as I-A-I) is a football stadium in Shimizu-ku, Shizuoka, Japan. It is currently mostly used for football matches and has been the home stadium of the J-League's Shimizu S-Pulse since 1992. The stadium holds 20,248 people and was opened in 1991. In November 2008 a four-year naming deal effective from March 2009 was announced expected to earn S-Pulse 360,000,000 yen. The stadium was known as The Outsourcing Stadium until February 2013. As Shizuoka City and Shimizu S-Pulse reached a 5-year deal with IAI Corporation, a manufacturer industrial robots, the stadium has been renamed as IAI Stadium Nihondaira effective 1 March 2013. This sponsorship deal was extended a further five years in 2018. History The stadium first opened in 1991 with the Main Stand as it appears today, with seating in front of grass banks on the other three sides. The initial capacity of seating was 13,000, rising to 15,000 with the grass banking included. In its debut year the stadium was used to host the football tournament of the annual All Japan High School Athletics Meet. In 1994 the stadium was substantially expanded, adding two-tiered stands behind each goal, and an enlarged Back Stand. In 1995 the capacity reached 20339. Following the installation of an elevator in the Back Stand, the capacity now stands at 20,248. Future expansion is far from impossible, although limited access to the stadium is the biggest hurdle. With the stadium not meeting J. League guidelines for the minimum percentage of seats covered from the elements, the club is exploring the possibility of building a new home. The stadium's pitch has received the award for the J. League's best kept playing a record nine times. This was in 2004, 2008, 2009, 2010, 2011, 2012, 2013, 2014 and 2015. The Best Pitch Award was abolished in 2016. When the stadium was built a score board was situated behind the east stand. This was moved to above the west stand following the 1994 expansion. This scoreboard fell out of use, and at the start of the 2007 season a new Astro Vision giant video screen was unveiled in the southeast corner of the ground. The former scoreboard has been repurposed as an advertising hoarding for the stadium sponsor. 2007 and 2008 saw S-Pulse host all home league games at Nihondaira for the first time since 1999. Prior to 1999 S-Pulse often played at the Kusanagi Athletic Stadium.