Pronto has been diversifying in recent years from simply being a coffee chain to also offering food and alcoholic drinks. They are currently offering a golden highball for 500 yen, which contains real gold leaf flakes. Gold leaf is actually not uncommon in Japan and can be sprinkled on foods to turn a fairly standard meal into something to talk about. Seeing it in drinks or having a national chain use gold leaf IS something unusual. The copy uses the phrase 大吉大利 which refers to good luck and prosperity in the new year. Obviously the image they are trying to convey. プロント ハイボール
Photo is a web capture for explanatory purposes, copyright belongs to the company.