Reina was a little girl with maroon hair that was tied with a yellow bow. She was seen wearing a red vest over a long-sleeved shirt.
Reina was very happy living with her mother and brother. She was very proud to have a protective brother like Kurt and wanted to marry him when they got older.
Chimera Ant arc
Through a series of journal entries written by Kurt; we learn various accomplishments made by Reina and her older brother Kurt. Reina is dependent on her brother and she hopes to one day marry him, which greatly embarrasses Kurt. Still, he worries about his younger sister's wellbeing and vowed to protect her from harm until she finds a worthy man. One day when Kurt and Reina go fishing by the riverside, they catch and cook some fish for their mother to give her a surprise. As they try to go home they're confronted by a giant crab-like Chimera Ant.
The journal monologue ends as the crab draws closer to the two children. While Kurt tries to defend himself and his sister with a stick, the Chimera Ant easily kills the children and delivers their remains to the Chimera Ant Queen; making them the first humans the Queen devours. Both Reina and Kurt are later reborn as Shidore and Colt; the desire to protect Reina was so strong that it was passed onto Colt and it has a great influence on his mentality. Reina and her big brother Kurt briefly appear again in a flashback with their mother Haruna.
- In Spanish, "reina" means "queen".
- In some emotional moments, Colt unconsciously changes "Queen" for "Reina".
- "Reina" is what Colt names Kite when he is reborn as a Chimera Ant girl.