I'm just a passing-through Kamen Rider. Remember that! (通りすがりの仮面ライダーだ。覚えておけ！, Tōrisugari no Kamen Raidā da. Oboete oke!)

―Tsukasa's answer when asked who he is[src]

Tsukasa Kadoya (門矢 士, Kadoya Tsukasa) is the main protagonist of Kamen Rider Decade. He is an interdimensional traveler who transforms into Kamen Rider Decade (仮面ライダーディケイド, Kamen Raidā Dikeido) to oversee the fate of the multiverse, embracing his role as the Destroyer of Worlds (世界の破壊者, Sekai no Hakaisha).