A time loop created by the Shocker resets whenever someone dies... but whenever the loop resets Shocker itself somehow grows stronger and stronger. It is up to Kamen Riders Drive, Faiz, Mach and Zeronos to decide whether to keep on fighting a useless battle... or end the loops for good by sacrificing one of their own.

Kamen Rider 4 is a web series which was released as an accompanying special to the film Super Hero Taisen GP: Kamen Rider 3. It introduced a new rider, Kamen Rider 4, who is the fourth Kamen Rider cyborg created by Shocker after Kamen Riders 1, 2, and 3. The plot goes around a time loop created by the Shocker that resets whenever someone dies, but whenever the loop resets Shocker itself somehow grows stronger and stronger. Thus, it is up to the Riders to decide whether to keep on fighting a useless battle... Or end the loops for good by sacrificing one of their own.

前(香取慎吾 飾)和司法重考生的太朗(松崗充 飾)還有小拳(加藤浩次 飾)三人居住在前的房子裡，過著單身的生活。一天，突然出現了一個被送到他們家的小孩五十嵐明(須賀健太 飾)要求正太叔父收養，他們三人便帶著明去找前屋主正太叔父，然而事情不如預料般順利，正太叔父拒絕了他們的情求，從此便開始了他們三人混亂的生活... 共同生活使他们对这个飞来的小朋友感情日益深厚，帮他学习，帮他学会与其他孩子相处。与此同时，也找到自己喜欢的人。一部温馨的家庭式友情剧。

在京都一带颇有名气的剧团导演海江田优儿（堂珍嘉邦 饰）毫不声张，悄然无息地和之前曾在同一剧团的恋人亚纪（高梨临 饰）结婚，开始了属于他们两人的爱情生活。在此期间海江田正在排演一部新剧，可是他的种种异样让剧团的负责人龙也（松冈充 饰）颇为担心。果不其然，某天海江田突然提出引退的请求，令龙也急于知晓背后的原因。与此同时，亚纪的妹妹阳菜（石桥杏奈 饰）在毫无征兆的情况下出现在海江田的面前，她的一番话让海江田的心布满阴霾。彷徨的一群人，心中各有所思……