He had a tattoo of the Shiba family crest on his arm. I've just became a Bleach fan recently and now started reading the manga and loving it!

I don't reject the theory that he has Shiba blood in him, which would at least explain the physical characteristics. Isshin Shiba. 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 wasn't just being literal. Ever wondered exactly WHY Ichigo looks almost exactly like Shiba Kaien? Als Kubo gefragt wurde, welchen Kampf er gerne noch einmal zeichnen würde, sagte er, dass ein Kampf zwischen Ichigo und Kaien ihm sehr gefiele, dies jedoch nicht mehr möglich ist, da Kaien tot ist. Kaien had a youthful appearance and was a fairly tall person.

It is stated that Ichigo Kurosaki closely resembles Kaien in appearance. Ichigo is a distant cousin of Kukaku, Ganju and Kaien but not Uryu. Ichigo, Isshin's son, just got un/lucky and ended up getting the same face as Kaien, and his build(slimmer then Isshin's) is close enough, combined with there hair …

Which brings up the important question. He had aqua green eyes and spiky raven black hair. Either Isshin or Masaki could have been from the Shiba family, taking the other's family name Kurosaki … Same for his sisters.

Ichigo Kurosaki (黒崎 一護, Kurosaki Ichigo) is a Human with Shinigami powers, the second Shinigami Agent, and the main protagonist of Bleach. Kurosaki Isshin, (Ichigo's dad) must have married into the name Kurosaki.

Kaien belongs to the Shiba clan, one of the four noble families of Soul Society. Anyway, Ichigo still could be related to Kaien. Kaien and Isshin are related although exactly how is unknown, if they are cousins, uncle/nephew, or what.

And what's worst is that Soul Society had caught wind that Kaien Shiba reincarnate had awaken and has his powers. Not memories of his past life. He wore the normal uniform with his lieutenant badge on his left arm as customary.

This can be quite simple, yet very relevative. There isn't much implication, but you can only assume by Isshin’s age that he is probably closely related to Kaien. If Ichigo was related to him, then that'd mean that he is a noble. I was more or less sure that Kurosaki was the surname of Ichigo’s mother since the Majesty (whom wiki named Yhwach for some reason) said that Ichigo was his son. Since three of the four noble families have been revealed, this can result into a shocking revelation. But I want to know if anyone has a theory for how Isshin Shiba and Kaien Shiba might be related, or at least how Ichigo is related to Ganju and … As the son of Isshin and Masaki Kurosaki, Ichigo possesses both Shinigami and Quincy lineages. He also inherited Hollow powers from his mother. This chapter was dedicated to the past Of Isshin Kurosaki, who now have a different name, by the way. Ichigo is related to the Shiba Clan but he is not a member of the Shiba Clan he was born to the Kurosaki family.