Tohka's relationship with her Inverse self is rather complicated, to say the least, as they had never directly met and are technically the same person. Following the first time she let Inverse Tohka take control, Tohka's views on her were rather negative, as she had nearly killed Shido. When Inverse Tohka was about to take control again during her fight with Origami, Tohka resisted, believing nothing good will come from letting her take over.
On the other hand, Inverse Tohka has shown to deeply care about Tohka. Though she did once indirectly insult her by stating that she is the "real" Tohka, as a Spirit's Inverse Form is their true form. Following the second time she took control, Inverse Tohka agreed to relinquish control back to Tohka, but only if Shido promised to never make her sad. When the two finally met during the fight against Mio, Inverse Tohka told Tohka about their origins and was fully supportive of her desire to protect Shido, despite knowing they would likely die.
Tohka was inadvertently created by Mio when she divided her powers between ten Qlipha Crystals, with Inverse Tohka even seeing her as their mother. Mio is even willing to praise Tohka's strength, citing that she always had a feeling Tohka would be the only one capable of opposing her. Despite this, like the other Spirits, Mio is still willing to kill her in order to reclaim her Sephira Crystal.
Tohka has very strong feelings for Shido and eventually comes to realize she loves him. As he was the first person to ever truly accept her for who and what she is, Tohka has become deeply attached to Shido, expressing great comfort and happiness whenever in his presence. As a result, she tends to get easily jealous when seeing Shido together with other girls (particularly Origami), which sometimes unlocks her sealed powers. Despite her insecurities, however, Tohka cares very deeply about Shido, almost always coming to his rescue to provide physical and even emotional support to him in his cause to save the Spirits, becoming especially close to the boy as a result. Tohka tells Shido that if she had never met him and learned how wonderful the world is, then she could have become just like Kurumi.
Tohka's attachment to Shido has been used against her on one major occasion. Following her capture by DEM, Shido, who had come to rescue Tohka, was seriously wounded by Ellen and almost killed right before her very eyes. The very thought of losing Shido, the person most dear to her, caused Tohka to become so overwhelmed by despair to the point of going Inverse. As a result of her transformation, Tohka, at first, seemed to recognize neither Shido nor her own name, and even attempted to kill Shido. Fortunately, Tohka was not beyond the point of saving, as she was brought back to her senses when Shido kissed her, further proving how truly deep Tohka's feelings of trust, care, and affection towards Shido runs. When the sealed powers of the Spirits causes Shido to lose control, Tohka finally came to realize her feelings for him, being able to describe it as the reason why she desperately wanted to save him.
Tohka dislikes Origami for many reasons; but most of the time, it has something to do with Shido. This dislike was shown to be strong enough that she would almost always call Origami by her full name.
In Volume 10, it is revealed that like Origami, Tohka actually began to get used to living with her. She eventually felt that her hatred and hostility to Origami had turned into something else compared to the first time she met her. This is proven to be truly shown when she didn't have the will to kill Origami even though the latter was seriously trying to kill her along with the other spirits. During the battle, Origami was able to defeat the spirits in their limited release Astral Dress. However, just as Origami was about to finish them off, Tohka manage to regain her full power and defeats her. In the midst of the battle, she stated that her [Hate] towards Origami wouldn't change but her [Hate] right now is most likely different from the old [Hate] she had back then. She even told her that if she wasn't careful, she will kill her.
After <Phantom> made Origami a spirit, she obtained many long-range abilities which made her a bad match-up for Tohka who mostly uses close-range abilities. During the battle between the two spirits, Tohka asked Origami if they could perhaps find a way to understand each other but Origami told her that she will reject all Spirits, including herself.
In Volume 11, Tohka temporarily loses her memory of Origami due to Shido changing the events that happened five years ago. Even so, Tohka still felt that something is missing, proving her relationship with Origami has been close throughout the half of the year. Near the end of it, with Tohka finally remembers Origami through her "pass" with Shido. Their relationship has shown to improve slightly, though, Tohka still sometimes acts in a somewhat Tsundere manner towards her. She also starts to use just Origami's first name more often, showing that she's learned to accept her more, but still views her as a rival for Shido's affection.
Tohka gets along very well with Kaguya and Yuzuru, especially Kaguya because of their similar energetic personalities. However, Tohka sometimes has issues understanding the two of them, because of the weird way each of them speaks.
Tohka first met Yoshino when she saw Shido attempting to make Yoshino fall in love with him so that he could seal her Spirit mana. Thinking Shido likes Yoshino more than her, which Yoshinon used to anger her, Tohka became furious and took the puppet from Yoshino. This action caused Yoshino to become distressed to the point of summoning her Angel <Zadkiel> in order to get Yoshinon back by force.
Despite their problematic first meeting, Yoshino forgave Tohka for her past actions and the two are now good friends after the former's Spirit powers were sealed. Yoshino is often seen together with Tohka when she isn't at school with Shido and the two act like sisters to each another.
Tohka and Kotori have an overall good relationship, as Kotori was the reason Shido was able to meet and ultimately save Tohka by sealing her powers. Kotori even let Tohka stay with her and Shido prior to the completion of the Spirit's apartment complex next to the Itsuka household.
However, like with Shido and the other Spirits, Kotori maintained her distance to Tohka because of her status as Ratatoskr commander. That was until the sealed Spirit powers inside Shido's body causes him to go berserk. Being ordered by her superiors to kill Shido should this happen, Kotori came into conflict with Origami, during which she finally let out all of the feelings she had been suppressing until that point. At that moment, Tohka and the other Spirits appeared before her, telling her she was not alone and that if she had any problems she should talk with them about them; ultimately convincing Kotori that they could still save Shido and to not follow her superiors' orders to kill him.
Ai, Mai and Mii are Tohka's classmates and appear to be her best friends. She often receives advice from them to help her with her relationship with Shido and they come to her aid whenever they think he does something wrong to her, which is often just a misunderstanding.
However, being ordinary civilians, Ai, Mai and Mii do not know of the existence of Spirits and that they are the cause of the space-quakes. As a result, they also do not know that Tohka is a Spirit.