The female protagonist is an alien whose ship accidentally crash-lands on Earth, thus causing Kaito to sustain fatal injuries. Since her bodily cells consist of thenanomachines the capacity of which is medical treatment, she saves him by transferring her cells to him through kissing and initially remains with him in order to be certain that he is in condition. Being an alien unaccustomed to life on Earth, her actions may seem weird in the eyes of others, but she is quick to correct herself if only to hide the fact that she is an alien. She was aware of Kaito's feelings, but had yet to respond with her own. She is kind, polite, friendly and an odd cook (because of her bizarre, yet still edible food combination choices). Like her best friend, Remon Yamano, she is a third-year student in Kaito's high school. Ichika later revealed herself that she is alien to Kaito and her friends, but it didn't bother them at all, especially Kaito who had a thought she was from outer space. With Kanna's help and influence, she confessed to Kaito and began dating him. Ichika said that she would continue loving Kaito, even after she left. At the end of the series, Ichika is shown in the final scene of the completed film, revealing that she was able to return to Earth again.