Shinobu Kocho/Relationships

Giyu Tomioka
Giyu and Shinobu are both Hashiras of the Demon Slayer Corps and they are usually assigned on missions together. They have opposite personalities and initially seem to be at odds with each other, as Shinobu appears to be under the impression that Giyu is an airhead and a klutz, assuming he is spacing out in front of a Demon as she is trying to save him. After he deflects her attack, she is angry at him for getting in the way and proceeds to remark that people dislike him as a result. However, Shinobu does wish Giyu would talk more. Despite all this, it is revealed in the second fanbook by Gyomei's comments on the Hashira that the two do enjoy talking to each other.

Later on, both her and Giyu come to care about the Kamado siblings and are visibly upset by the hostile treatment of the other Hashiras towards them. When Giyu later hears about Shinobu's death, he suddenly recalls her smiling face and is visibly shocked at the news.

Tanjiro Kamado
Shinobu first meets Tanjiro after she attempts to kill Nezuko, and tells him it is dangerous to be so close to a Demon. Later on, during the Hashira's trial, she is the only one trying to hear Tanjiro's side of the story, and has a sad expression on her face as Tanjiro desperately tries to explain that Nezuko has not and will not hurt anybody.

She comes to care about both Tanjiro and Nezuko and is visibly concerned about them, even letting them rest at her estate so they are able to recover from their injuries. Tanjiro is visibly sad when he hears about Shinobu's death.

Zenitsu Agatsuma
Shinobu meets Zenitsu during the Natagumo Mountain incident, and treats his wounds after he has slain one of the spider demons. Shinobu also tries to motivate Zenitsu by cheering him.

Inosuke Hashibira
Inosuke meets Shinobu while recovering at the Butterfly Estate. To motivate him to continue his recovery training, Shinobu condescendingly mocks his inability to do simple things, prompting Inosuke to angrily train harder. As time passed, Inosuke saw Shinobu as a surrogate mother due to her kindness. After knowing that Doma killed Shinobu, Inosuke becomes mad at the Demon and joins Kanao in her battle to defeat him.

Murata
Murata first meets Shinobu at Natagumo Mountain when she rescues him from the Older Sister Spider. As she has seen Murata naked, he's been avoiding her since then.

Kanao Tsuyuri
Although Shinobu was the one to impulsively buy her adoptive sister Kanao out of slavery, she quickly became frustrated when Kanao could not make her own decisions, declaring that she was dangerous to herself and others. However, Shinobu soon warmed up to her and developed a strong, sisterly bond. During Kanae’s funeral, Shinobu comforted Kanao and was understanding of her inability to cry.

Shinobu eventually made Kanao her chosen Tsuguko (successor) due to her considerable talent and exceptional skills as a Demon Slayer. Shinobu instructed Kanao to cut off a demon’s head without thinking, though she was worried whether or not Kanao was truly following her own will. But when Kanao begins opening up and expresses her wish to train beside her specifically, Shinobu is very happy.

Shinobu holds great trust in Kanao, as she entrusted her with avenging Kanae’s death while using herself as a sacrifice. She is also noted to be protective towards Kanao; Inosuke mentions that Shinobu gets “really mad” when Kanao gets hurt, and Shinobu expresses her worry about Kanao using the Flower Breath’s Final Form and thus possibly losing her sight, even when she was the one losing her life. When Shinobu dies at Doma’s hand, Kanao successfully avenges her with the help of Inosuke.

In the aftermath, Shinobu and Kanae later give their blessings to their younger sister before departing to the afterlife. This causes Kanao to break down in tears for the first time. Kanao also keeps both Shinobu and Kanae's butterfly hair accessories as mementos of their lives, and continues holding both of them in high regard.

Kanae Kocho
Shinobu was noted to have a very close and loving sisterly relationship with her biological older sister, Kanae having been seen to be very close to each other since early childhood and having spent their childhoods happily together with their parents.

The sister's bond was incredibly deep and caring, as seen where the two of them both took an oath to protect others from demons and ensure no one else goes through their tragedy upon the two of them surviving the Demon attack that killed their parents. During this time the sisters developed a unique familial dynamic, where Kanae would frequently make lighthearted, whimsical decisions without thinking first, which then causes Shinobu great expiration and worry due to her elder sister's behavior. But Shinobu is still shown to trust her sister deeply and support her sister's decision despite not initial agreeing with her at first, as seen when the two adopted and made off with their adoptive little sister Kanao Tsuyuri.

Later, Kanae's deep love for her sister was truly shown during her last moments after fighting Doma, where Kanae begged Shinobu to leave the Demon Slayer Corps and simply live her life free and happy, stating that the only thing that would make her happy is knowing that Shinobu would be able to live a full happy life and die peacefully as an old woman, showing just how much she loved her younger sister. Shinobu in turn showed her own immense love for her elder sister by swearing that she couldn't possibly live like that and begged her sister to tell her which demon killed her, swearing eternal vengeance against whoever killed her sister.

Mitsuri Kanroji
Shinobu and Mitsuri are good friends. However, Shinobu has expressed jealousy towards Mitsuri's strong body before. Nevertheless, they remain on good terms.

Tamayo
Although initially Shinobu harbored little trust in her due to her status as a Demon, Shinobu gradually began developing a sense of respect for Tamayo as they began working together on a drug that can finally destroy Muzan, as seen where Shinobu was genuinely impressed at Tamayo skill as a doctor and fellow poisoner and was truly appreciative of her skills due to them making it possible to successfully create their Anti-Kibitsuji Drug that successfully weakened Muzan enough to death. Tamayo herself was even willing to assist Shinobu in her quest for vengeance by helping her modify her body to be saturated in Wisteria Poison for the battle against the Upper Rank 2, showing that by that time, Shinobu had already seen past Tamayo's status as a demon and had truly come to trust and admire her as a fellow doctor.

Doma
Shinobu holds a strong resentment and hatred for Doma, due to him killing her older sister, Kanae. This hatred and disgust becomes even stronger when she actually meets him and comes to understand and see first-hand his twisted personality and ideas about giving his disciples "salvation" by killing and eating them. Later, during their battle, she continuously curses him due to him not being affected by her poisons and sword techniques again and again, until she is defeated and devoured by him. However, thanks to Shinobu's body being heavily saturated with poison, Doma is severely weakened and is eventually successfully slain by Kanao and Inosuke.

Inside of Limbo, Doma, having heard and been touched by Shinobu's strong faith and belief in her comrades and fellow Demon Slayers' ability to defeat the demons and slay Muzan, seemingly begins to develop genuine feelings of romantic attraction towards Shinobu. He begins to doubt his initial belief that neither heaven or hell or paradise exist, and happily asks her if she wanted to go to hell with him for a date, to which she responds with sharp rejection while having the usual kind and calm smile on her face as a final act of spite towards the Demon.