Mental illness in the world today is something that needs to be addressed seriously in order to support the lives of many people. In Germany, Turkish immigrant children live through an identity crisis because they feel far from "home". The process of searching for self-identity due to the huge cultural differences between west and east give rise to feelings of stress and depression as a characteristic of mental illness in adolescents. Therefore, Zoë Jenny through her novel Ein Schnelles Leben (2002) carries the theme of the diary as a representation of the search for selfidentity. Ein schnelles Leben (2002) by Zoë Jenny also conveys that feeling far from "home" is something that must be resisted in a way that can keep the sufferer alive, such as by writing. In this study, the author uses a descriptive research method by presenting a complete picture of the state or social phenomena presented in the novel Ein Schnelles Leben and supported by theories about diaries and personas to find out the importance of identity and the various personalities (public masks). There are three sections in the analisis: a) Das Blaue Buch as Story Telling Media. b) Persona and Intertextuality in Ein schnelles Leben, and c) Das Blaue Buch's Role in Identity's Formation. The result is that diary in the process of searching for self-identity proven to be able to provide happiness because it is often chosen as an "escape" by the main character.