shonen, or shounen (少年) anime (shows like Naruto, Dragon Ball, My Hero Academia, etc.) all (for the most part) realize a certain set of values, which are usually central to their plots and which the main character usually embodies. These values are things like perseverance in the face of great obstacles, believing in one-self and having hope that anything can be accomplished no matter the circumstances, determination, aiming to be the best at whatever it is the character does (being the best ninja, being the #1 superhero, etc.), and so on. This set of values seems very specific to shounen anime to me (a seinen anime, such as Durarara!!! does not have these values as central themes of the show).
This always seemed odd to me, because this seems like a very individualist set of values, and Japan (from what I know) is traditionally a collectivist society. I was asked to leave these terms out, but I don't think I can without taking away from the question, so I'll do my best to define what I mean by them.
By "collectivist", I mean that, from the viewpoint of the culture, individuals are defined in terms of a larger group (their families, their religious group, etc.), and consequently, ethics which emphasize the importance of that larger group is realized (in things like protecting the honor of a family, for example). That is what I mean by collectivist.
By "individualist" on the other hand, I mean that, from the viewpoint of the culture, individuals are not seen as part of a larger group, and consequently, an ethics that promotes the individual is realized.
I've always seen the set of values (the "ethics") embodied in shounen as more individualist, because the emphasis in the shows always seems to be on the main character realizing these values for themselves, and when there is a conflict between the main character wanting to be the best and keeping the ties with others that they've formed along the way, the former usually wins out. For example, in Naruto, in one of the beginning arcs, Naruto fights a man named Zabusa, who has a character named Haku by his side. Over the course of the arc, Naruto comes to learn that Haku is similar to him in many ways and comes to have empathy for him. Haku wants to kill Naruto, because at this point, as he sees, his "dream" is to fulfill any wish Zabusa has. Naruto's "dream" on the other hand is to become Hokage (the highest ranking a ninja can have) and to do this, he has to succeed in his missions. He kills Haku, precisely because he sees Haku as an obstacle to his goal of trying to become Hokage. It's in that sense that I mean the values are "individualist"; the individual of the show and them trying to become the best seems to take priority, and things like family bonds or friendships have a secondary importance.
So, given all that, where do these ethics come from, and how did they end up in a Japanese medium? More specifically, is there any historical connection in older sources that could be tied to this ethics coming into shounen anime?
I asked this question on the anime stack exchange, but no one was able to answer, so I thought this place might be better.