Let's start with the basics: the following is Isshin's little character page, given to us by Kubo Tite. These facts can not be disputed. (And I really like these character pages, too, they're filled with fun and pointless facts!)
Blood Type: AB
Date of Birth: December 10
- Head of Kurosaki household
- Local doctor. Can do anything except major surgery
- Likes potato bean paste cakes
- He was actually supposed to be a mortician instead of a doctor until the very last minute this manga was published, so he looks better in a black suit than a white lab coat
- Theme song is Don't Drag Me Down by Social Distortion, recorded in White Light, White Heat, White Trash. [listen]
Isshin comes crashing into Bleach at the very start of the series, greeting his son with a kick to the face. And while this is not the usual way of doing things in polite society, it certainly is typical of the energetic and often violent Kurosaki family. Of course, Isshin is hardly normal, and neither are his parenting techniques. Father to super saiyan Ichigo and twins Yuzu and Karin, all of his children first appear to be more mature than their father. Both Ichigo and Karin regard him with derision at times. Sometimes they just skip the derision and go straight to kicking him. The Kurosaki family like to kick. Isshin's wife and mother of his children, Masaki, was killed some years previously. A large and slightly creepy memorial poster of her hangs in the Kurosaki household, to which Isshin asks advice when his children get too much for him.
The Kurosaki Clinic is headed by Isshin. Shockingly enough. It appears to get all manner of patients, and is attached to the family home. All the children seem to help out at the clinic, with Yuzu even having her own very cute nurse outfit. As dorky as Isshin can be at times, being a doctor is Serious Business! And thus, Isshin in doctor mode is our first glimpse of his serious face. And his serious face is always there, lurking beneath the jovial and immature surface. There's a lot more to Isshin than one would ever expect, even leaving aside the super surprise Shinigami revelation.
The most important thing to him is clearly his family. Many times during the manga he expresses concern for his daughters and verbally enquires after their welfare. With Ichigo, he's slightly more covert, and he certainly sees a lot more than he lets on. And he knows what exactly is going on, almost from the very beginning. But more of that later. All in all he's a good, if slightly unconventional, parent who has done quite well raising his children alone after the death of their mother and the woman he loved. If you consider letting your teenage son run around with a large sword fighting soul devouring spirits as "quite well", but I'm sure you do.