This is a fishing tool called "Sao Yasume Fune II" by YAMASHITA. It costs ¥1,079 (tax included) on Amazon. It is used by inserting it into the rod holder hole on the side of the boat. It's a convenient item for when you want to put your rod down for a moment while fishing, or when you need to take your hands off the rod to handle fish or bait. It has a function to prevent the rod from sliding sideways or falling due to the movement of the boat or wind. The bright color makes it easy to find even if you accidentally drop it. Thank you for viewing.