Casca is the love interest of Guts in the manga and anime Berserk.
Casca was the only female soldier in the original Band of the Hawk. She at first hated Guts, because she felt he stole her role as the right hand of her commander Griffith. However, Casca eventually fell in love with Guts. They consummed their relationship before rescuing Griffith from prison after he slept with the princess.
Unfortunately, after the trauma of the Eclipse, especially her rape at Femto's hands, Casca is now insane, she even lost her memory and speaking abilities. Guts' current goal is to find a cure for her insanity.