The databook only says that it's bandaged to remind himself of his bond with Sasuke. It never mentions whether there are any other reasons for it. His arm isn't covered in the movie's epilogue or in the wedding portrait or photos of the kids, but there's no way to know whether it's a mistake or real, and it looks normal.
Well, put it this way: he's behind a desk all day with access to the internet and his wife looks and acts like the frigid type so "alternate" methods of relief are necessary. The bandaged arm is his dominant arm but it's also an arm where wounds could easily open up if he thrusts too hard, that's where the bandages come in.
The databook only says that it's bandaged to remind himself of his bond with Sasuke. It never mentions whether there are any other reasons for it. His arm isn't covered in the movie's epilogue or in the wedding portrait or photos of the kids, but there's no way to know whether it's a mistake or real, and it looks normal.
In the Retsu no Sho movie guidebook that was distributed to moviegoers.
The page with the arm:
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I'll edit this post when I find the translation.
Kay, I couldn't find where I read that but I will say what I remember from memory. Something like "Though at first glance the bandages seem lame, his tightly-wrapped right arm is a reminder of his bonds with Sasuke." So it actually reveals nothing about the arm and is only making a statement about the design, like they wanted to put in some kind of visual reminder of what happened into his design. It is a character design page after all.
I don't think they would have wanted to just go with a different skin-color because it's a black-and-white comic and the design needed to work in that format. They don't even need to deal with the background behind why it stays that way as long as it never comes up in the story. It's possible he hasn't spent any time thinking about it.
You can BYOT (bring your own translator) because the page is right there. I would've transcribed it myself but I can't even read the furigana in the scan.
