The Anthopper Imagin are a pair of Imagin brothers named Ari and Kirigiris and the main antagonists of episodes 30 and 31 of Kamen Rider Den-O.
Ari was voiced by Kōsuke Toriumi, and Kirigiris was voiced by Tomokazu Seki.
The two Anthopper Imagin were sent to destroy Den-O, choosing Yuya to be their contract holder.
As part of their plan, Ari lured Den-O to a railway for their trap and ambushed him, only to be beaten back by Gun Form until Kirigiris appears to assist his brother in overpowering Gun Form. However, Yuto sends Deneb to assist Den-O, causing the two brothers to resort ot a different plan.
Ari uses Fujishiro to abduct Airi and leaves a message challenging Den-O to fight him and his brother at the Mitsuboshi Factory if he wants Airi to be returned alive. Yuto and Deneb go instead to save Airi, but Yuto hesitates to transform as it would use his last card.
Momotaros-Ryotaro then shows up and transforms into Den-O Sword Form to fight the Anthopper brothers alongside Deneb. Yuto also decides to join in, transforming into Zeronos for his final time. Zeronos defeats Ari while Den-O assumes Climax Form and destroys Kirigiris.