In 1954, Godzilla kickstarted the kaiju genre in Japan called the "Monster Boom", which remained extremely popular for several decades, with characters such as the aforementioned Godzilla, Gamera and King Ghidorah leading the market.[2] However, in 1957 Shintoho produced the first film serial featuring the superhero character Super Giant, signaling a shift in popularity that favored masked heroes over giant monsters called the "Henshin Boom" started by Kamen Rider.