June is from a visual novel called Wizardess Heart.

June is the childhood friend of the protagonist. June is actually Joel's child version, however was forced to live life as a girl for his survival. Had his father not forced him to pretend to be a girl, Joel would have died, as there was an evil wizard who hunted and killed male children with Joel's ability. June's/Joel's ability is spell singing. Throughout their childhood, June was a very caring and supportive friend to the protagonist, being there for her when her parents passed away. June left the protagonist one day, and erased her memories. Because of this the protagonist has forgotten the promises that they had made together. 

Voice: Very young and childlike. Example