|Японское имя:||古賀 いたみ|
Blood Type: AB
Itami Koga is a junior of Class 13 and a former member of the Flask Plan's Thirteen Party. Her project name is Best Pain. She is the only member of the Flask Plan who was originally a Normal.
Koga was originally an Normal so she had a normal life. She thought of the normal world as "too normal" so she went up to Youka Naze and asked for change. She loves Naze deeply as a friend and is always with her, even when she's making poor decisions or has experimented on her.
Voiced by: Madoka Yonezawa