Eiji's motivation to continuously search for information about his father can stem from several emotional and psychological factors:

1. Desire for Connection: Eiji may feel a deep longing to connect with his father, especially if he has been absent from his life. This search can be driven by a need to understand his father's identity and the reasons behind his absence.

2. Curiosity and Identity: Understanding his father can be crucial for Eiji's own sense of identity. Many individuals seek to learn about their parents to better understand themselves, their traits, and their place in the world.

3. Unresolved Questions: If Eiji has unanswered questions about his father's life, choices, or circumstances surrounding their separation, this can create a compelling drive to seek out information. The need for closure or understanding can be a powerful motivator.

4. Emotional Healing: Searching for information about a parent can also be a way to process feelings of abandonment, loss, or grief. Eiji might hope that finding out more about his father will help him heal emotionally.

5. Family Legacy: Eiji may be interested in his family history and legacy. Learning about his father could provide insights into family traditions, values, and stories that are important to him.

6. Hope for Reconciliation: If there is a possibility of reconnecting with his father, Eiji's search could be motivated by hope for reconciliation and the desire to build a relationship.

These motivations can vary greatly depending on Eiji's personal circumstances, his relationship with his family, and the context of his father's absence.