I don’t buy that Sakura went his entire childhood with absolutely no one caring about him before Furin. Kids don’t raise themselves. How did he survive? Who fed him, taught him, protected him? The gaps in his past are too big.
Nonnie, I'm going to give you the benefit of the doubt that you're here to be legitimately confused rather than trying to antagonize me and I will give you a genuine response here.
First of all, I want to genuinely express how happy I am for you that you sound lucky enough to not know any better. The fact that you don't buy it sounds like you've lived a decent enough life that, even if not perfect, was still filled with enough people that cared that you cannot wrap your head around the idea that this could happen to anyone.
I, on the other hand (and also many other fans of wind breaker I believe), have not been so lucky. First and foremost it's very important that you understand that the concept of caring for someone's basic essential needs (food & shelter) are not equal to caring on the level of affection and love. Human beings need both. It is very important to development.
Kids can and do often absolutely raise themselves sometimes but let's just focus on Sakura's specifics for a second. I don't think everything has been fully revealed and even then I think some things are left vague and unknown so I may be guessing in some ways but I'm trying to go with what we do know.
Let's start with his essential needs:
Who fed him? Probably his caretakers did feed him because that is a legal expectation of caretaking a child or at minimum he was fed a school-required lunch and got by on that alone (considering his interest in eating food it could be a reaction to not having access to food a lot when younger)
Who taught him? For book smarts/academics, likely school teachers of course. But otherwise, Sakura has been shown on multiple occasions to not know how to act in certain moments. So in a lot of cases the argument could easily be made that no one did. Some quick examples: he struggles to use cutlery properly, during the Shishitoren battles its obvious there's a social hierarchy order to the fights that Sakura is not aware of and has to keep being reminded about, he doesn't know how to interact with people positively (he doesn't understand handshakes), he doesn't know how to act at funerals which I think is a thing that Japanese families usually teach children at some point (dont quote me on that one tbh) etc.
Now I'll interject here because I'm sure in your confusion you're thinking still that its not possible that no one taught him these things. Unfortunately, it is wholly possible. From personal experience I can attest that there were many things growing up that I was not taught because my parents were negligent and abusive. If the people taking care of you are spending most of their time making you regret being born/treating you like a burden with their words and actions, they are not dedicating a lot of extra time into teaching you how to act or exist. At best you learn by watching and even then, if you are isolated in an environment that is simply filled with people who will not let you close, you're not going to get the chance to watch much of anything.
Who protected him? Another one for the "no one did" pile. The most "protection" Sakura seemed to receive was in the form of a roof over his head. Beyond that it is both implied and blatantly said that Sakura was subject to relentless bullying (at the very least from fellow kids, if not also caretakers and teachers) that was not stopped by any sort of authority that should've done something. He was also subject to verbal and emotional abuse (if not highly implied physical abuse as well) so his guardians were doing zero in the protection department either.
Interjecting once more to insert personal experience with a "yes this does happen to kids". I was relentlessly bullied for a variety of reasons throughout my entire time in grade school, this was never stopped by authorities and often encouraged bc I was considered a "nuisance" and bad kid for those very same reasons I was being bullied. (Sakura is known to be bullied over his appearance at the very least but also very likely for his inability to interact socially due to already built up issues from prior to school age developments).
These are just the essential things that he was not getting. And I'm going to continue below the cut into the blatant lack of care in the form of any sort of affection or "warmth"
















