Nor any known citizenship system in both factions. In place of both slavery and hard labor (health-decrease), a laborer, working class, or the related is a viable alternative. Closest are Simöbe/Yatuko (both mean "servant") and Siduwo ("lower-class man"). The ones normally rendered "citizen" can use either Tunepitö (ordinary man), Pitö ("man"), or Otöna ("adult").
"Caste" is a misnomer, especially in Indian contexts; best to research the concept of varna in this case. Also debatable is slavery in ancient India, especially during the Buddhist/Maurya timeframe. For now, Dāsa (male)/Dāsi (female) in reference to servants/workers/bondsmen.
Also, revert defense_tower back to Yagura because Takatönö actually refers to a "high or tall palace (building)" instead of actual stone tower; can't find any attestation about any latter per se.