Chase Tomari, known as Kamen Rider Chaser, is a major character in the series Kamen Rider Drive. Originally a Roidmude named Proto Zero, Chase starts as an antagonist called the Grim Reaper, enforcing the Roidmude's will. Over time, he regains his humanity and allies with the protagonist, Shinnosuke Tomari. As Kamen Rider Chaser, he fights to protect humans and struggles with his identity, becoming a key ally in the battle against the Roidmudes.