zenkaikon was formed in 2006 by the merger of two philadelphia-area events, zentrancon and kosaikon. in 2008, zenkaikon became a two-day convention. in 2009 due to significant attendance growth, zenkaikon moved to the larger valley forge radisson hotel (same complex as its former location the scanticon) and capped attendance at 1,500 attendees per day. in 2010, zenkaikon announced it would become a three-day convention, move to a spring date (skipping 2010), and increase convention space by using both the valley forge convention center and scanticon hotel and conference center (same complex). the changes were made to improve weather, allow for better preparation, and increase staff. during the convention in 2011, zenkaikon and its attendees raised $3750 for the american red cross japanese earthquake and pacific tsunami relief fund. due to construction of the valley forge casino resort at the valley forge convention center, zenkaikon 2012 was held at a new location, the greater philadelphia expo center at oaks, and reduced to two days.