At some point, some boys and girls began to embody their own ego ......, through which they demonstrated their ability to directly interfere with the minds of others. The unprincipled youths enjoyed playing games with each other, battling their egos and absorbing the power of the other. On the other hand, there are those who don't like the fact that the possessor of an ego invisible to ordinary people is on the loose. Ryo Matsuura has lived his whole life without knowing what happened to him, but before long he too became able to see the Ego. However, with the help of his best friend Shuji Fushimi, who is also an egoist, he is able to escape. As soon as he gets used to his new environment, Yae Shibaura gives him a powerful power, and Ryo is forced to think about what to do with himself. Ryo's understanding of ego is deepened as he helps Shuji hunt down a psychic who plays with it. However, he is horrified to find out that his estranged lover, Hotaru Ashida, is also under the spell of the psychic who is after him. On the other hand, Shuji continues to work alone without informing Ryo, and in the process, he gets to know a solitary girl, Saya Miyaji. One day, Yae, who is supposed to be dead, appears in front of Ryo and tells him that she wants to talk to Shuji. Ryo is troubled and tells Shuji about it, but when Shuji meets Yae, he decides that what she is trying to do is dangerous. Shuji challenges Yae to a fight on his own, loses, and never wakes up again. Ryo confirms his love for Hotaru, who still cares for him in spite of the danger, and decides to face Yae himself. Satoko and Naomi, who are fascinated by her, try to block Ryo's way, but Haruaki and Saya join them and let him go first. Yae confronts Ryo and tells him that she has taken countless egos into her body and will realise them for the sake of everyone's happiness. Stripped of the power she has given him, Ryo's ego reverts to its pre-growth form, but his determination to run as far as he can finally reaches Yae. But it is a path from which there is no turning back, and the two disappear in a blaze of glory. As Hotaru waits for Ryo's return, she receives a final message from him on her mobile phone.