Umamusume character. Resident mad chemist of the series.
Horse girl. Has short, messybrown hair with a prominent ahoge bent backwards at an odd angle. Also has red eyes with conspicuously missing "eyeshine" that are 'marked' with strange horizontal grid-like patterns. Tachyon also wears a single earring on her right ear in the shape of the chemical structure of indane*. (*Hexagon fused with a pentagon with lines running inside the hexagon. This is often mistakenly drawn as two fused pentagons.)
Tachyon most salient trait is her long lab coat, worn as part of her racing outfit. This labcoat has so-called "moe sleeves" running past her fingers, as well as striped patches on the upper sleeves. The hip section of the coat is festooned with two pairs of 'throwing bandoliers' filled with corkedtest tubes containing a mysterious glowing blue liquid. Unlike most other Umamusume characters, Tachyon also tends to wear this labcoat together with her school uniform.
Character-wise, Tachyon is usually portrayed as an unethical mad scientist with a penchant for developing shady drugs, then testing them on The Trainer or the other uma-girls, the typical result being them turning into human/equine glowsticks. In true (Japanese) mad scientist fashion, she refers to others using either -kun or kimi. She also calls The Trainer "guinea pig". Her mad scientist trait is actually motivated by finding a cure to her fragile legs before she is crippled for good. This is based on the fact that the original horse had his very successful career cut very short by leg injuries.
Her real-life counterpart is named after the tachyon, a hypothetical faster-than-light particle.
-kun and kimi as used by the "mad scientist" archetype usually comes across as being somewhat overly familiar and uncomfortably 'endearing' (i.e. the mad scientist tries to act friendly, but their body language and actions are anything but). Often this also has a slight touch of (unintentional) condescension. The English equivalent would be using "my friend" or "my dear [INSERT NAME]", said by somebody who obviously doesn't have your best interests in mind.
She makes more Kamen Rider references than other uma-girls.
RL mates. Both were often involved in a netorare situation with Tachyon in fan works. Primarily due to their other mates, Seiun Sky and Kitasan Black, were unpopular studs compared to Tachyon.
