Chifumi Takahashi

Takahashi Chifumi is a human from the Diaclone continuity family.

Doctor Takahashi Chifumi, also known as C-Tach, is Aquarius's assistant.

Fiction

At some point, Chifumi found herself in Axiom Nexus, unable to return to her home universal stream. She eventually encountered Aquarius, with whom she made a deal: she retrieved a shard of the Star Saber from the vaults for him, in return for safe passage home. Transformers I.Q. last issue review #6 The pair arrived instead in Primax -408.24 Epsilon, which Chifumi pointed out plainly was not the right universe. The truth became clear moments later—Nexus Prime had transported them there to pick up a package. Transformers I.Q. trivia bonus #12 However, Ultra Magnus refused to hand it over, citing his duty as its guardian to personally safeguard the Matrix until he could personally meet Nexus Prime. Another Light: Falling into Place

Doctor Takahashi was one of several Japanese scientists to contribute to the creation of the Trainbots. Ask Vector Prime

Takahashi Chifumi is based on the Diaclone pilots that came with Transformers back when they were part of that line, specifically the pilot that came with the Diaclone version of Sunstreaker; the toy's name is "Countach LP500S", hence Chifumi's nickname of "C-Tach". She is unnamed in the Transformers I.Q. comic strip, with Aquarius addressing her as "Dorothy" as part of a Wizard of Oz metaphor.
As per the ordering used in the Japanese language, Takahashi is the character's family name while Chifumi is the given name.
It is unclear if the Doctor Takahashi mentioned in Ask Vector Prime refers to this known dimensional traveler, or to a Generation 1 continuity family analog of her. Knowing Vector Prime, he'd probably say they were the same being regardless.