Eejanaika (ええじゃないか) is a steel fourth-dimension hypercoaster at Fuji-Q Highland in Fujiyoshida, Yamanashi, Japan. The ride opened on 19 July 2006 as the world's second fourth dimension coaster. Eejanaika is taller, faster, and longer than its predecessor, X2, at Six Flags Magic Mountain.
The roller coaster, designed by S&S Arrow, is a fourth dimension coaster, a design in which the seats can rotate forward or backward 360 degrees in a controlled spin. This is achieved by having four rails on the track: two of these are running rails while the other two are for spin control. The two rails that control the spin of the seats move up and down relative to the track and spin the seats using a rack and pinion gear mechanism.
Eejanaika's official Japanese spelling is stylized, with the second "え" kana being turned upside down. Eejanaika has several meanings, but is most commonly translated to "Ain't it great!" in English. According to the Guinness Book of World Records, Eejanaika ties with The Smiler at Alton Towers for the world record of most inversions in a coaster, as both coasters contain 14 inversions. However, this is disputed, because 11 of Eejanaika's inversions are inversions of the seat, rather than inversions of the track, and all of The Smiler's inversions are track inversions.
Eejanaika's tracks were initially painted red with black supports, but following the addition of Mount Fuji to the UNESCO World Heritage List as a cultural site in June 2013, Fuji-Q progressively repainted its tracks to the current dark brown with grey supports between 2013 and 2014. Its trains were also updated.