Tokiko is a fairly short character with orange eyes and blue shoulder-length hair. Her most distinguishing feature is the horizontal scar running across the bridge of her nose and across her cheeks. She is most commonly seen wearing the Newton Apple Academy for Girls uniform which is a blue and white sailor outfit with white cross designs and an orange bow. She also wears similarly designed knee length socks and white shoes. In more casual situations she wears a green shirt with a turtle-neck collar, yellow shorts and brown heeled boots.
Tokiko is a fairly serious character, and can barely tolerate the antics of Kazuki and his friends. She becomes irritated easily especially when people ask about her scar or about her relationship with Kazuki. She often threatens those who annoy her with her Valkyrie Skirt. She is also somewhat sensitive about her naval.
She bears an extreme hatred toward the Homunculi due to the trauma of her past. Her hatred has made into a merciless but dedicated fighter as she furiously shreds Homunculi with her Buso Renkin while saying her catchphrase, "I'll splatter your guts!" Such as the case with Jinnai she will even torture some Homunculi to make them experience the same pain they inflict on others before finishing them off. This hatred also extends to those associated with the Homunculi such as the Hayasaka twins when they were Familiars of the L.X.E. as she was determined to kill them despite them still being human and unable to fight at the time. She was merciless even against Kazuki when he tried to stop her from harming the twins. Though her scar could have been easily removed by the power of alchemy, Tokiko had decided to keep it as a reminder of her desire to kill all Homunculi.
Her top priority is her job and the protection of others as she brought Kazuki back to life using a Kakugane and was even willing to commit suicide before transforming into a Homunculi. She is very dedicated to her job, having quit going to school in order to be more efficient. She dislikes getting others involved in her business and often prefers to fight alone. Her favorite spot is the water tower at the top of Ginsei Academy where she is often seen when she wants to be alone.
She felt a distinct attachment towards Kazuki when he was killed trying to save her and used the Kakugane to bring him back to life. She often admires his positive attitude, increasing strength and fighting spirit but can be annoyed at him when he is acting goofy. She cares about him greatly, getting deeply upset when he is seriously wounded and even mourned for him when she thought he was dead. Over the course of the series she falls in love with him as she decides that she will die when he dies and even kisses him near the end of the series.
As a young girl, her school was attacked by Homunculi. All the people in her school were killed or eaten by the Homunculi apart from herself, leaving her as the only survivor and was eventually found by Mamoru Sakimori.
Sometime afterwards she trained to become an Alchemist Warrior and eventually met and taught Gota Nakamura.
During one mission she infiltrated Newton Apple Academy for Girls where she found and retrieved Kakugane LXX (In actuality a disguised Black Kakugane III). Sometime later she was sent on another mission in Ginsei City.