Himiko is the series' main female protagonist. Her real name is Hemilia. She is a high school girl who is also Btooom! player and was Ryōta's in-game wife, though they did not notice this at first. She has feelings for Ryōta and cooperates with him in the Btooom! game. Years before the series present when Hemilia was in high school, she was befriended with Yoshioka-senpai and his band, which was well known and popular among the high school girls. One day, she invited her friends Miho, Arisa and Yuki to meet them in their apartment after school to which they accepted. Hemilia then left to go her apartment that was located in the same building to grab some last minute snacks. When she came back, she came across the remnants of a party with traces of alcohol and drugs on the table. When passing by the bedroom, she saw two members of Yoshioka's band raping Arisa and Yuki while Yoshioka filmed them. Yoshioka turned to Hemilia and tried to drug her as well by kissing her with the drug in tongue, but Hemilia punched him in the face and ran away. As she ran, she saw Miho getting raped. Miho shouted for Hemilia to save her, but Hemilia ran out of the apartment where she quickly called the police. Eventually, she is nominated by former classmates to participate. Upon meeting Ryota in real life and discovering the truth about him, Himiko is able to overcome her fear of men. After professing their feelings for each other, Himiko and Ryōta try to have sex, Ryota comes to the realization it isn't correct to do it now, so instead they vow to return home to become a couple in the real world.