This paper attempts to clarify how the "modern girl" became an ideology, to explain the actual conditions under which it became an ideology and to investigate what kind of changes followed. The popular magazine Shojo-no-Tomo is analyzed from two different points of view. The first concerns how the family is emotionally interrelated. The second concerns the "girl's" position in such a family. The results of the analysis are as follows. From the end of the Meiji Era through the end of the Taisho Era, the relationship between the girl and her family was one in which there was a unidirectional, absolute devotion from the girl to her parents, which became the basis for the parents affection. This is traditionally known as "ko". However, starting at the beginning of the Showa Era, the relationship changed from "ko" to a relationship of modern affection and devotion, where the parents did not expect girls to reciprocate their affection with absolute devotion. As time passed, this bond of affection was expanded and strengthened. Thus, with the encouragement of family members, girls learned to pursue freedom and self-realization, by being set free from the restraints of "ko", and were able to give priority to considerations of themselves. That girl's image was different from the image of ryosaikenbo ("good wife, wise mother") that was taught in schools. During the War, this new identity served the girls well, as they were able to make contributions to the state as independent individuals with emotionally support from their families. The conclusions of this paper show the process by which the "girl" within the family has become an independent and personally involved "national." Therefore, within the family, the change of emotional relations has brought forth a new independence, which in turn expresses a change in the way that the "state" and the "individual" relate to one another.