With less than a week left before the Tokyo gubernatorial election on Sunday, Gov. Yuriko Koike remains in the lead but with her main challenger Renho at her heels and dark horse candidate Shinji Ishimaru also building momentum.

Polling data by all major news sources collected over the weekend showed that the 71-year-old incumbent continues to be the most popular of the election's 56 candidates — albeit by a small margin.

Koike is being backed by the ruling Liberal Democratic Party, while Renho has the support of the main opposition group, the Constitutional Democratic Party of Japan (CDP), making the Tokyo vote something of a proxy war for the national political parties.