Dr. Jiro Toshiwa is a human scientist working at the Ascension Project. With a reputation of being a charming and easy-going young man, Jiro is of American and Asian descent and is described as good-looking and fit. Despite an age difference of nearly twenty years, he's in a non-serious relationship with Kahlee Sanders. Though Hendel Mitra is suspicious of him, Jiro is one of the few people Gillian Grayson appears to trust and feel comfortable around.

However, this is a facade. Jiro is actually a Cerberus operative, planted to monitor the progress of the Ascension Project and pass information to the Illusive Man. His relationship with Kahlee is a lie: Jiro is only using her to get information. When Cerberus wants to push ahead with their experiments on Gillian, Jiro is to secretly administer a dose of neurostimulant to her. The first dose makes Gillian unleash a biotic storm in the cafeteria; as Jiro is absent, he later asks Kahlee about it while they're in bed together. He convinces Kahlee not to let Gillian be taken from the Ascension Project, but makes a mistake by mentioning Kahlee's father: the fact that Kahlee is Jon Grissom's daughter is only known in classified Alliance documents which were filed by David Anderson.

By the time Kahlee realises this the next morning, Jiro has already sneaked Gillian out of the Academy's hospital and to a secluded spot to administer the second dose. However, this time he injects it into Gillian's spine and the drug causes a seizure. Jiro is caught when Hendel Mitra arrives and orders him away from Gillian. While Hendel is distracted by Gillian's condition, Jiro uses his standard-issue stunner to shock Hendel unconscious. Fleeing the scene, he runs into Kahlee and is incapacitated after a brief struggle.

After being captured, Jiro is questioned by the Alliance. Though he manages to hold out under harsh interrogation, he eventually admits he is a member of Cerberus, though he doesn't reveal any details about his mission. Jiro's ultimate fate is unknown; as Paul Grayson knew, Cerberus occasionally rescued its operatives when they had been captured, but Jiro would likely have been considered expendable.

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