She made her
World Championship debut at the
2003 Winnipeg World Championships playing lead for
Shinobu Aota's team from Japan. She would return to the world championships in
2004 with the same team. Her next World Championships came in
2008, where the Japanese women (along with Team China) became the first team from the Pacific region to qualify for the Playoffs at the World Championships. Ishizaki and her team, skipped by
Moe Meguro, defeated
Team Switzerland in the
3 vs. 4 Playoff match. In the Semifinal, they nearly defeated Team Canada and went to the Bronze Medal match to face a rematch against Team Switzerland. They would lose this match 9 - 7, which would become the second-best performance by a Pacific region team at the Curling World Championships. Kotomi Ishizaki played Lead position for
Team Japan at the
2010 Winter Olympics. and at the
2010 Ford World Women's Curling Championship. Ishizaki was chosen as an alternate member for
Team Japan at the
2022 Winter Olympics, in which they won first-ever silver medals. Ishizaki became the oldest Japanese athlete to win a medal at the Winter Olympics at age 43 years and 1 month, surpassing
Noriaki Kasai, who won 2 medals at the
2014 Winter Olympics at age 41 years and 8 months. == Teammates ==