Ichigo Takes After His Self-Sacrificing Father, Isshin Shiba
Ichigo and his goofy father Isshin always butt heads, but deep down, they deeply respect one another, and Ichigo saw his father in a whole new light when he learned the truth about how his parents met. Some time ago, Captain Isshin Shiba was sent to the world of the living, where Sosuke Aizens artificial Hollow White ran amok, threatening the life of Masaki, a young Quincy archer. Isshin risked his life to save hers, and when Whites Hollow powers poisoned Masaki, Isshin risked it all yet again. With the aid of his friend Kisuke Urahara, Isshin gave up his Soul Reaper powers to save Masakis life once again. Isshin had no qualms about sacrificing his entire career as a Soul Reaper to save this innocent girl, and in the years to come, the two of them married, and Ichigo, Karin and Yuzu were born.
Likewise, Ichigo never hesitates to leap into danger to protect his friends, even if the odds are seriously stacked against him. He stormed the Soul Society with a small gang of friends to rescue Rukia from the Gotei 13, the most powerful soul-oriented force in existence. Later, Ichigo was ready to invade the world of Hueco Mundo alone to rescue Orihime from Ulquiorra, and Ichigo faced Ulquiorra twice in mortal combat and nearly died both times — but it didnt matter; Ichigos friend needed him, and the Shiba way called for a brave sacrifice.
It is possible, because the series has not gone into enough detail about reincarnation, except for the one filler of the dog, my theory is that when Rukia stabbed her shikai into Kaien, his soul split into 2 places, in Hueco Mundo, and within Rukias shikai, this could explain the time when Kaien told Rukia that part of him will be with her, maybe he wasnt just being literal. Then when Rukia stabbed her zanpackto into Ichigo, the merge of her soul with his, created his Zangetsu. Although this is just a theory an Anime Theory. (edited by AkasukeKitsuneForever)
Isshins last name is Shiba. He married Masaki whose last name was Kurosaki which is a Quincy family name seeing as she was a Quincy and he basically took her name when they married and went undercover for the past 20yrs. No one knew where he was. Prior to that he was a branch head of the Shiba Clan and the former 10th Division Captain before Hitsugaya. In Japanese nobility a branch head basically means hes the younger brother of the main family head and thus he is Kaien, Kukaku and Ganjus uncle (which they insinuated when they sent ichigo to the royal palace with the royal guard) and therefore Ichigo, Karin and Yuzu are their cousins. (edited by Salubri)
Ichigo and Kaien Shiba Both Have Plenty of Heart
Kaien Shiba was Ichigos cousin, and he was a popular Soul Reaper in squad 13. It was he who helped refine Rukia Kuchikis skills, and he gave Rukia an extra lesson: that the “heart” is the immortal bond between two people, and should one of them die, they will live on in the other persons heart. Rukia fully understood this after Kaien died and she saw Aaroniero Arurruerie assume his form, and she slew the imposter Kaien without hesitation, since the real Kaien lived on in her.
Similarly, when Orihime was told that Ichigo and the others had invaded Hueco Mundo to rescue her, Orihime was not afraid for their sake. She knew that the heart that connected them would allow them to prevail, and Orihime bravely told Ulquiorra that Ichigos heart wouldnt allow him to die. Ulquiorra doubted this, but he changed his tune when Ichigos heart allowed him to slay Ulquiorra at long last. In his dying moments, Ulquiorra was desperate to see this “heart” phenomenon for himself.
Does Kaien come back to life?
Is Kaien Ichigo’s father?