Aozaki Touko

Aoko's older sister. She studied magecraft under her grandfather, but murdered him over the shock of having the Aozaki inheritance usurped by her younger sister and fled to the Association. Unlike Aoko, her abilities as a magus are top class. She has even received a sealing designation due to her status as the world's greatest puppet master.
She does not appear in Tsukihime. However, she is a key figure in Kara no Kyoukai, which intersects with Tsukihime.
Tohno Shiki's mystic eye sealing glasses originally belonged to her.
She is merciless, just like Aoko. Honestly, do these Aozaki folk not have a single decent person among them?

Tsukihime Data Collection: Tsukihime Dictionary
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She looks like a woman in her late 20s. Touko is the guide in this tale, yet at the same time she is an outsider. The owner of the Workshop, Garen no Dou.
She is one of the magi that appear in this tale, and makes a living by crafting puppets.
Touko is an individual with dual personalities, and the switch is made by putting on and taking off her glasses. With her glasses on, Touko is objective and ruthless; yet without her glasses, she is subjective and emotional. Which one is the real Aozaki Touko, even Touko herself does not really know. Emotional or not, Touko is fundamentally a romanticist.
Touko loves new things, and will tinker restlessly with things that she is interested in. She is also a speed demon.
Although Kara no Kyoukai will not be a story without Touko, she does not constitute the body of the tale.
Touko hates her name, yet she has a habit of always wearing one piece of orange-colored accessory.
Even though Touko has a younger sister, their relationship is extremely bad.

Garden of sinners Pamphlet: Kara no Kyoukai Settings Glossary
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Aoko's older sister. She studied magecraft under her grandfather, but murdered him over the shock of having the Aozaki inheritance usurped by her younger sister and fled to the Association. Unlike Aoko, her abilities as a magus are top class. She has even received a sealing designation due to her status as the world's greatest puppet master.
She does not appear in Tsukihime. However, she is a key figure in Kara no Kyoukai, which intersects with Tsukihime. Tohno Shiki's mystic eye sealing glasses originally belonged to her.
In retaliation for having her prized mystic eye killers stolen from her, she's been making an effort to buy as much stuff as she can under Aoko's name. Then, even the Association has entered the era of e-commerce?
…Even though there's a high chance of her location leaking out if she keeps it up, it seems that revenge against Aoko even takes priority over her own self-preservation. Geez, Touko, you should try to be a little more mature.
By the way, her name shows up for just a second in Fate/stay night, too. Is she secretly trying to win the prize for perfect attendance?

Tsukihime Dokuhon Plus Period: Tsukihime Dictionary Revised