Rukia Kuchiki
Ichigo has a unique, complex, and dynamic relationship with Rukia: At times, they are bickering adversaries, and at other times, despite these quarrels, the two have a deep understanding of each other, often giving each other a considerable amount of emotional support when needed. It is seen that at times Ichigo cares about her. Most of their scenes together involve them yelling and making faces at each other, regardless of where they are or who's witnessing their 'confrontations', friends, allies, and enemies alike. They also share similar feelings of loss and guilt: Ichigo thought he was responsible for his mother's death and Rukia's near-execution, while Rukia thought she was responsible for the death of one of her commanding officers , and considered Ichigo's apparent death during her fault. In battle, as seen during the first two movies, Ichigo and Rukia work near-flawlessly together. It is worth noting that their love-hate relationship has some romantic feelings. In the third movie, the movie had made it clear that Ichigo probably has some feelings for Rukia.
Kisuke Urahara
He owns the shinigami-item-selling Urahara Shop, is former captain of 12th Division, and was creator of the Hōgyoku. He is highly intelligent, always knows more then he lets on, and is a guiding force throughout the series, often helping the Ryoka in their missions. Kisuke tends to be rather secretive towards Ichigo, neglecting to tell him about the Hōgyoku, and not informing him of his knowledge that Ichigo's father Isshin was once a Shinigami (though, Isshin himself might've requested it, but it's still unclear). Despite his frequent annoyance with Urahara, Ichigo still seems to respect him, readily identifying the former Captain as being his sensei when asked by Ikkaku Madarame.
Renji Abarai
The second Shinigami Ichigo encounters (Rukia being the first). They initially viewed each other with contempt during The Sereitei Conspiracy, despite wanting to prevent Rukia's execution, and repeatedly fought each other during the Ryoka Invasion, but later become friends as the story progresses. Renji and Ichigo tend to have the same views on life and have virtually the same personality, making some mistake them as brothers a number of times during the Bount arc. To keep things simple, Ichigo stated that they're "cousins". Throughout the series, Renji helps Ichigo on several occasions, such as preventing Rukia's execution and fighting the Espada, despite his loyalties to the Soul Society, though they can engage in verbal confrontations with one another, similar to Ichigo's relationship with Rukia.
Byakuya Kuchiki
Ichigo initially views Byakuya as something of a monster for allowing Rukia's execution to take place, but later changes his opinion of him after their battle in the Sokyoku Hill. Though now allies, Byakuya doesn't particularly like Ichigo, especially because he doesn't use honorifics when addressing him and refers to him by his given name, which Byakuya finds insulting and annoying, much like Histugaya. However, Byakuya still respects him, despite not using any honorifics, and views him as valuable ally against Aizen and the arrancar. The same could be said for Ichigo.
Yoruichi Shihōin
When first encountered, she is in the form of a small black cat with a deep male voice, initially leading Ichigo and the others to believe that she was a male until she transformed. She helps Ichigo and his friends infiltrate the Soul Society during Rukia's execution. Prior to the execution, she helped Ichigo learn his Bankai in three days through a special kind of training for his battle with Byakuya. During this time, she transformed in front of Ichigo (twice in the anime), amused by his reaction. The two typically have a fair amount of respect for one another and will often assist each other during their battles against the arrancar, usually through training, medical assistance, or actual fighting. The same is true with Urahara.
Kenpachi Zaraki
Kenpachi was the second Shinigami and first captain that Ichigo fought (excluding Byakuya). They both respect each other (even though Ichigo only calls him "Kenpachi") and consider each other allies, despite their earlier fight. Kenpachi's personality traits parallel Ichigo's and due to their (subtle) similarities, Kenpachi will give insight to the inward struggle Ichigo has, while he seems to contend with, as seen during Ichigo's Vizard Training. One may even state that, due to their similarities, Kenpachi, like Kaien, Renji, and Grimmjow, is what Ichigo may be if he had embraced both his inwardly animalistic self, and the incredible power that his inner hollow wields, instead of fearing and disregarding it. However, Kenpachi apparently craves a rematch with Ichigo, due to the fact that he was the only person to have beaten him in combat, and always challenges him to a duel whenever off-duty. Ichigo himself does not wish for a rematch, however, (likely because he no longer has a reason to fight with the 11th Division captain), and tends to run away whenever asked for another fight, even feeling his will to fight him from far away.
Soifon
Ichigo has no interaction with Soifon in the manga, but in the anime, they've encountered each other in Bleach: The DiamondDust Rebellion and again during the New Captain Amagai Arc. During the Kusaka Incident, Ichigo breaks through a barrier that Soifon set up and questioned a crime scene. Soifon states that there's "normally no reason to explain the situation to a substitute", but she decides to tell him the information she knows anyway. It's unknown if she did this because of the respect Ichigo's earned from the Soul Society, or if it's because of the degree of the crime (involving the security of the powerful King's Seal). During the Amagai arc, she and the 2nd Division attempt to stop both him and Rukia from stopping the wedding between Rurichiyo Kasumiōji and Shuu Kannogi. She then admits that she had some respect for Ichigo before then and questions his actions for stopping the wedding, but she lets him speak to Rurichiyo, who then claims the she didn't know him (though, this later turns out to be an imposter). While she respects Ichigo for his combat prowess and accomplishments, she holds great disdain towards his refusal to adhere the Soul Society's laws.
Tōshirō Hitsugaya
Hitsugaya and Ichigo had little interaction throughout the course of the series, and Ichigo consistently refers to him as "Tōshirō", which Hitsugaya finds both insulting and annoying, repeatedly stating that "the proper way" to address him is to call him "Captain Hitsugaya". However, despite this and their rare interactions, Hitsugaya has some degree of respect for Ichigo, assisting him in Senna's rescue, and explains to his sister (during the Arrancar Arc) that although he doesn't have knowledge of Ichigo's whereabouts, he's confident that Ichigo's working to get stronger. During the movie Bleach: The DiamondDust Rebellion, Ichigo aids the then rogue Tōshirō, unconvinced that he has betrayed Soul Society to help Sōjirō Kusaka. When the final battle occurs, Ichigo tells Tōshirō of his feelings concerning his mother's death, that are much like his own concerning Sōjirō.
Jushiro Ukitake
Although they have rarely interacted, Captain Ukitake displays great respect for Ichigo, and initially seemed to notice the boy's close resemblance to his former lieutenant. Having been grateful for Ichigo's help during the Soul Society arc, Ukitake presented him with the substitute shinigami badge so that he could continue fighting hollows in the world of the living without relying on the use of a ginkongan. He also noted during a conversation with Shuhei Hisagi that Rukia became much more sociable after encountering Ichigo and his friends,most likely due to his resemblance to Kaien. During the Amagai arc, Ukitake has been shown to willingly disregard direct orders from General Yamamoto in order to help Ichigo succeed in whatever task he has set upon himself to complete, the same is true with Ukitake's former colleague and closest friend, Captain Shunsui Kyōraku. Again, all this might stem from Ichigo's nearly-identical resemblance to Kaien, both in regards to their appearances and personalities, and Ukitake was one of Kaien's closest friends.
Shigekuni Yamamoto-Genryūsai
As the leader of the Gotei 13, Yamamoto respect Ichigo's abilities as a shinigami, but looks down upon him for his refusal to adhere to the Soul Society's laws. In turn, Ichigo shows little-to-no respect for the old general, publicly referring to him as "gramps", even in face-to-face conversation. The only order that Ichigo ever received from Yamamoto was to remain in Karakura Town, and not to rescue Orihime Inoue, vow branded as a traitor, after she is kidnapped by Ulquiorra, but he promptly ignores this command and heads out with his friends without the formal consent of the Soul Society. Despite this, Yamamoto later sends four captains to Las Noches to assist them, ultimately saving their lives, while also dividing and weakening the offensive forces of the Gotei 13. During the Amagai arc, Yamamoto also witnesses Ichigo's hollowfication during his battle with Shūsuke Amagai, but displayed no signs of hostility towards the boy after the fight.
