This study reviewed the trends of self-pluralism and identity formation studies. Recently, the study of self-pluralism has gained popularity and some researchers have suggested that self-pluralism has increased in today’s youth. Youth with self-pluralism easily adapted to various scenarios of the society. In Erikson’s identity theory, self-pluralism causes conflict. Intrinsically, self-pluralism was regarded as the opposite of identity. However, modern youth who are classified as having self-pluralism do not feel conflicted. In other words, the modern youth seem to have both a sense of identity and self-pluralism. These youth appear to have multiple identities. The purpose of this study is to consider multiple identities from various perspectives. Changes in society and Japanese culture are associated with multiple identities. The identity formation of modern Japanese youth cannot be explained by Erikson’s identity theory. Therefore it is necessary to examine identity and self-pluralism as a variety of forming processes in future studies.