At Hinata House, Keitarō meets Naru Narusegawa, who is also studying to enter Tokyo University.
Naru ranks first in the whole of Japan on the practice exams, and Keitarō convinces her to help him study.
After a while, Mutsumi moves to Tokyo, and the three begin to study together.
During this period, Naru becomes convinced that Mutsumi is Keitarō's promised girl, but Mutsumi states that she made a childhood promise with Naru, not Keitarō.
However, he has forgotten the name of the girl he made the promise to and hopes to be accepted into Tokyo University in order to find her.