Season 11

A man named Tsugami Shoichi has lost his memories. He doesn't know who he is, where he came from, or how he came upon his peculiar circumstances. Seemingly for no reason, hew transforms into a powerful superhuman, Agito, whenever in the presence of the beings referred by the police as the "Unknown", a race of powerful monsters that have been causing murders around Tokyo, targeting certain people as their prey. In response, the police department unleash their newest weapon: the G3 powersuit. G3 and Agito don't know whether they should join up and defeat the Unknowns, their common enemy, or to combat each other, keeping the mysteries that entwine them separate. Ultimately, more mysteries unfold with the appearance of Kamen Rider Gills, who is on a search to uncover why his father committed suicide. These mysteries and others collide, as the true nature of Agito would ultimately determine the fate of humanity.

“未確認生命体事件”の終息から2年の月日が流れたある日、沖縄県の与那国島海岸に人知を超えた謎の遺物・オーパーツが流れ着いた。 同時に各地において、人間には不可能な殺害方法を用いた猟奇的連続殺人事件が発生する。警視庁はこの事件の犯人を、かつての“未確認生命体”を超える新たなる脅威として「アンノウン」と命名し、未確認生命体対策班 (SAUL) に専属捜査を命じた。 この物語は3人の仮面ライダー、SAULに配属された若き特務刑事・氷川誠＝G3、瀕死の重傷を克服した後に変容していく自らの肉体に恐怖を抱く大学生・葦原涼＝ギルス、そして記憶喪失でありながらも本能の赴くままにアンノウンを倒していく家事手伝いの青年・津上翔一＝アギト、の物語を交差させ、やがてひとつの巨大な流れへと昇華していく。

A história se passa 2 anos após os eventos de Kamen Rider Kuuga. Uma nova série de misteriosos assassinatos começa na cidade de Tóquio. A polícia, que já suspeitava que pudessem ser "Formas de Vida Não Identificadas" (como eram chamados os Grongis, inimigos de Kuuga), criaram o G3 System, um sistema de defesa que habilita um usuário a utilizar uma armadura de combate com poder suficientemente alto para destruir as criaturas.

因为不可能的犯罪，人们会发生奇怪的死亡的事件。那是身份不明的怪人“未知生命体”所引起的。从属于警视厅“未确认生命体对策班”的冰川诚，装着被称作G3的强化战服迎击，却被怪人的惊异的力量所玩弄，而被逼进绝境。而在陷入穷境的G3前，金色的战士“AgitΩ”出现了……。失去记忆的青年·津上翔一与游泳选手·苇原凉的身体发生异变。AgitΩ、未知生命体、欧帕兹之谜。随着新的战斗的开幕，翔一隐藏的过去也渐渐明朗起来。