Leading a expedition in Thuringia, Germany, Kougami Kousei was unearthing the resting place of one of the First OOO's alchemists to obtain legendary Lost Medals. However, upon the seal being undone, millions of Cell Medals erupt into a tower while creating a magical barrier that causes parts of Japan to flip over. This attracts Hino Eiji's attention as he and Ankh investigate. Arriving as Knights emerge from the tower after it dragged Kougami and Satonaka Erika in, Date Akira arrives as Eiji and he become Kamen Riders OOO and Birth to battle the Knights.