Kawaguchi previously competed as a singles skater for Japan, then switched to pairs and skated with Alexander Markuntsov. They teamed up in 1999, and were the first Japanese pair team to medal at an ISU championships, which they did at the World Junior Figure Skating Championships in 2001. She is fluent in Russian and English. She attended university in Saint Petersburg and studied international politics. In December 2008, she acquired Russian nationality to earn an Olympic berth.