Kunijima Chiaki

The main protagonist of "Kouyoku Senki ExS-Tia Concerto 4"

An introverted and quiet girl. She's smart and surprisingly strong-willed. And when she believes in something, she puts her heart into it.

She's not very sociable and was bullied as a child, but Kanon saved her and they have been best friends ever since.
She feels like Kanon is the only friend she has, and aware that she is a little too dependent on her, so she thinks it would be better if she distance herself from her best friend.

However, she discovers that she has high PP abilities, and in order to change herself, she cooperates with Ichika and became an ExS-TIA.

Translated from Official Site

Later revealed that she has romantic feelings for her best friend, Oosumi Kanon