Ikumi Akagi

The heroine of Volume 11, first appearing in Volume 9. She is a first-year student in the medical nursing department at the same university as Sakuta. She has a bob haircut. She was in the same class as Sakuta during their third year of middle school and reunited with him at the university's entrance ceremony. She wore glasses at that time, but has since taken them off when they met again.

She is not very talkative, and when she does speak, it is in a calm and composed manner. She has a strong sense of justice and responsibility, and tries her best to respond when relied upon by others. She is enthusiastic about committee and volunteer activities, and is considered a prude with a strong aversion to the opposite sex.

In middle school, she barely spoke to Sakuta, and had not met him since he started attending Minegahara High School until Volume 9, when Sakuta experienced a different world, where she was also a student at Minegahara High School. There, she was one of the few people who spoke normally to Sakuta, showing signs of being conscious of him.

After speaking to Sakuta at the university entrance ceremony, they hardly saw each other or spoke, as they were in different departments, but in Volume 11, they interact in an unexpected way. Also, when Sakuta went to a different world, it was revealed that Ikumi, who was a student at Minegahara High School in that world, and Ikumi, who originally belonged to Sakuta's world and attended a different high school, had switched places and were attending university. These two Ikumis were suffering from a syndrome of adolescence where they wanted to "escape somewhere," and they could share sensations such as pain and touch. They also wrote messages on their bodies to share information with each other.

Both Ikumis continued to live a more fulfilling life in different worlds than before, but according to Sakuta's guess, Ikumi's aversion to impurity did not allow the act of "escaping," and they returned to their original worlds.

Ikumi from another possible world

In her third year of middle school, she felt envy and her own powerlessness after seeing Sakuta solve a bullying issue against Kaede by himself in that world.

Later, she attended the same Minegahara High School as Sakuta and became friends with Saki, who was in the same class during their second and third years of high school. She also observed Sakuta closely and realized that he had solved the problems of Mai, Tomoe, and Rio, and felt that it was Sakuta, not herself, who had become the person she wanted to be, leading a life of envy. She also failed her university entrance exams and thought of "escaping" to another possible world, where she became a freshman at the university where Sakuta was (and where she reunited with him). She continued her life as a university student, engaging in activities such as volunteering and helping people based on prophetic dreams she saw on social media, feeling that she had become the person she wanted to be.

Having no experience in dating, she was unlike the other Ikumi, having no immunity to the opposite sex.

Ikumi from the original world

As a model student, she tried to be helpful in her first and second years of class, but felt powerless when she couldn't do anything during a bullying issue against Kaede in her third year of middle school, which led to a phenomenon of adolescent syndrome that attacked Sakuta and Kaede, and the class turned against Sakuta. She attended a different local high school (a public academic school). Kotomi was her junior in middle and high school. In high school, she was involved in activities such as being the student council president. At one point before graduation, she lived at her boyfriend's (Seiichi Kosaka) house instead of returning home, commuting to school from there.

At the university entrance ceremony, seeing Sakuta, who seemed to have recovered from the middle school issues as if nothing had happened, made her feel embarrassed about still being haunted by her middle school days and unable to show her current self, leading her to think of "escaping," resulting in her switching places with Ikumi from another world. The Ikumi from that world had taken a gap year, so she never met Sakuta at university, and because the bullying issue with Kaede had been resolved in that world, she felt relieved and continued to live in that world.

Ikumi from the other possible world was even less talkative, especially about herself, and tended to speak only the bare minimum necessary. Having had a boyfriend, her demeanor towards Sakuta and others showed a familiarity with the opposite sex.

Feeling a strong responsibility for the warning message sent to Mai and Sakuta from her other self, she went as far as to accompany Sakuta to Hokkaido when he needed to meet Takumi (Volume 13).