Tsukasa Taira is the female protagonist of the Devils' Line series. She is a first-year graduate student at Keio University where she originally studied Humanities and Geography. She is a kind-hearted human girl who falls in love with Yuuki Anzai at almost first sight. Despite the difficulties of being in a devil/human relationship, she stays positive and is always trying to make it work. She cares about Yuuki and his suffering as a devil very much and is constantly looking for something she can do. After becoming more aware of the devils' situation in society and learning more about them, she is thinking about studying sociology and about devil problems, as she thinks that devil problems are human problems as well. Tsukasa is a young woman noted to be beautiful, with a short and petite figure, standing at 153 cm. As noted by Juliana Lloyd, she seems to have quite the bust despite her short stature. She has short, light-brown hair which freely falls down to her neck, tucked behind her ears, and side-bangs that she lets frame her forehead. She has brown eyes. In Line 6, she is wounded when she tries to protect Anzai from shattering glass from Zero Seven's bullet. The wound starts on the left side of her nose, drags diagonally downward, and stops below her right eye. The scar is permanent. After the three-month timeskip, Tsukasa's hair has grown longer and is now nape-length. Her bangs are also rather messy and have grown longer, in which it now frames her face more than before. After the six-month timeskip (in a total of nine months), Tsukasa has grown longer bangs and she also cut her hair to lower-chin length, styled into a bob-hairstyle. Tsukasa is a very gentle, caring and kind-hearted person, and is accepting of people whether they may be humans or devils, stating that all of them are the same. She is quick-witted and has relatively good instincts, but she is very slow on the uptake when people like her. Tsukasa is very responsible, mature and capable of the things she is good at, and wants to help people in fields where she can be helpful. This is why she wants people to be straightforward with her and frankly tell her what she should and shouldn't do since she doesn't want to tie people down, especially Anzai. She is very patient and supportive of people, and has a strong sense of right and wrong. She is almost never seen being angry at other people and usually carries a calm demeanor. Although she was relatively oblivious to the devil matters in society, she has grown to understand more about them and is able to sympathize with them due to her relationship with Anzai, whom she loves deeply. She is positive and is always trying to make her relationship with Anzai work, and she is very loving, devoted and supportive of him and accepts him just the way he his. And even though she has involved herself in more dangerous and serious matters; like being targeted by the CCC and almost getting killed, Tsukasa has developed more as a person because of this, as she has grown more mentally strong, persistent and stubborn. She will stand up for herself and will firmly hold on to her own opinions and things she wants to do; she is always ready to take action, especially when it comes Anzai's safety. She is also very straightforward and will speak and move without hesitation; she always faces people head-on. After learning more about devil problems in society, she is interested in changing majors to sociology instead and study self-defense. It is mentioned that she became a private tutor and that she spent a lot of time in the lab, and Tsukasa claims that she does these things because she wants to. This shows that Tsukasa is hardworking, and she also hopes that doing these things will give her some real results. After a long time of feeling anxious about her future, Tsukasa has found something she genuinely wants to do. At times, a childish and meek side of Tsukasa can be shown. However, it is noted by Anzai that Tsukasa can say some really "wild" and "vulgar" things in their love-life (which can make Tsukasa herself embarrassed sometimes), and she also appears to be very straightforward in their relationship. At times, she is rather lively and she was initially portrayed to comically "hit" people such as Anzai when they insulted her, as for example when Anzai once said that she was skinny and would be more popular if she ate more.