She first appears when Midou Kusabi failed to kill Tsukune. After wounding him with her needle finger, she took control of the doctor. She then attempted to use him to inject the same substance into Moka. After she smashed a vase to his head, Mako injected the substance into Moka and used her to cut Tsukune before Kurumu intervened. Feeling angry already, Kiria Yoshii told Mako they would work together. She angrily rejected his offer and took control of innocent bystanders in the infirmary, to which Kiria mentioned she has impulse issues. When Tsukune wanted to talk to Moka about the incident, he ran into Mako who used the bystanders to attack him. Moka then intervened before Mako could kill Tsukune. After Tsukune pulled off her rosario cross, Moka at first doesn't transform due to the substance Mako used to control her. After Tsukune talks to Moka, she jabs herself, transforms, and defeats Mako. (U.S. manga translation called her a "Mongrel" alluding to the mixed heritage of a Monstrel)
In Alucard's return, Mako reappears along side with Midou defeating one of Alucard's clones in the final battle.
Mako gives Yukari an older body after she complains about the body she has. Mako at first makes Yukari happy. However Mako later reveals that she only gave Yukari an older body to make her negative thoughts stronger. Though it isn't seen, a battle between Moka and Mako occurs. After Mako is defeated, Yukari returns to her old self again.
Mako Yakumaru has a needle finger, in which every time she injects someone with whatever fluid(?) that is in there, they do her bidding. In the anime version she was able to make people older.