89

89 is a member of the Shadow Garden, being one of the Numbers.

Background
559 once challenged 89 to fight her, so she could have the right to challenge Numbers. Knowing that 559 had just joined the organization recently and the difference in numbers was over four hundred gaps, then she shouldn't have a chance of winning. But the 559 had won with an extraordinary victory against her and gave her the right to challenge the Numbers, even a high-ranking "Named Numbers" member.