In an ancient Period, the Diksha guru performed his role as:

In the ancient Indian education system, the Dīkṣā Guru was responsible for initiation (upanayana/dīkṣā) and imparting spiritual and religious instruction.
This role was traditionally restricted to male students, as formal Vedic initiation and gurukula education were mainly meant for boys. Hence, the Dīkṣā Guru functioned as a spiritual guide of boys, not a secular tutor or instructor of all subjects.