Every April, a prayer ceremony is held to mark the start of the tourist season, during which the chief priest offers a prayer for safety and prosperity at Lake Shikotsu for the year. The key monument, which symbolizes the opening of the lake, signifies "the key that opens the door to the tourist season at Lake Shikotsu."

In addition, young kokanee salmon, affectionately known as Lake Shikotsu Chips, are offered as offerings. You can enjoy gourmet food and activities around Lake Shikotsu, and from late April you can also enjoy swan boats, and the area becomes lively with many people driving around the lake.