Yoshika was born to Daisuke and Aiko Agata on July 27th, 2519. Brought up as her parents' only child in the city of Nagoya, Yoshika displayed anti-social tendencies early on and was diagnosed with a form of autism before she was two years old. The effects became more noticeable when she continually re-opened a cut on her shoulder from climbing to reach a quartz crystal that eventually scarred over, this repeated self-injury frightening her parents. Later on, however, she became very close friends with a child from her neighborhood named Reika Fujimoto, and as they interacted more often, the symptoms of Yoshika's autism became less noticeable. By age four, she had caught up with and even surpassed the developmental markers for her age and was deemed recovered from the disorder.