Yumi, known as Sayaka in Japan, is Kei's (supposedly) twin sister. A rising star, headed for the music business, she has a good singing voice and excellent physical coordination.

Despite being twins, Yumi's appearance is very different from Kei's (not necessarily uncommon, as their different genders indicate they're fraternal twins, not identical).

At the beginning of Ape Escape 3, she is one of only the humans who haven't fallen prey to Specter's latest scheme, along with her brother Kei, their aunt Aki, and Natalie.

She has the same Morphs as her brother, though they obviously deviate in appearance.

Apparently, Yumi has a rivalry of some sort with Monkey Pink.

Yumi also seems to have a fan club among Specter's monkey minions, since a number of monkeys that would run away from her brother simply fall on their behind with huge hearts in their eyes if they catch sight of Yumi.

She is the 1st female playble in the games (so far). 

In fanon contextEdit

She once mentioned Kei is now able to sing. However, Kei's secret relationship with Depty Durland of the Gravity Falls Police department disintegrated the false alarm.