thanksgiving shrine visit
A visit to a Shinto shrine to express gratitude, often after a prayer has been answered or a wish fulfilled.
願いが叶ったので、神社へ礼参りに行った。
Since my wish came true, I went to the shrine for a thanksgiving visit.
Compound of 礼 (rei, 'gratitude') and 参り (mairi, 'visiting a shrine'), the nominalized form of 参る (mairu, 'to go to a shrine').