memorial mound for unknown persons
A burial mound or grave marker erected to honor and pray for the souls of unidentified or unclaimed deceased individuals.
To pray for the souls of the bodies washed ashore, the villagers built a memorial mound.
Compound of 供養 (kuyō, 'memorial service') and 塚 (tsuka, 'mound'). The reading づか is a rendaku form of つか.