Where is the option of the report for the “Custom Object with related object” in Salesforce?

If the parent object is the standard object provided by the salesforce like “Account”, “Contact” then the report will be in there section with related custom object.
If both objects are the custom then the report will be in “Other Reports” Sections.

Following are the conditions to get the report of related objects:

On both the objects, Reports option must be enable.
Both object must be related either using Lookup or Master Detail type of field.