Usually when I make these "is it cyberpunk" posts, I try to pick movies that are popular enough that I can assume most people have already seen them. I'm not sure if Summer Wars is at that level but I wanted to ask this question anyway. Because really, there's only one aspect to this movie that could be considered cyberpunk and that's the inclusion of cyberspace.
It seems to me there are two types of cyberpunk: the hard-boiled detective in a futuristic city of neon lights, and stories involving cyberspace. For example, Tron and Lawnmower Man don't have any aspects of cyberpunk in the "real world" parts of the movie, yet both heavily rely on cyberspace. So both movies (I believe) are considered cyberpunk.
I'm taking that distinction and pushing it to the extreme with Summer Wars. In the real world parts of the movie, this is a slice-of-life story about a girl going to a family reunion and trying to convince her family that a friend of hers is actually her boyfriend. They're a middle-class family meeting up in a rural region of Japan. Basically as far from cyberpunk as you can get. But then there's the cyberspace part of the story, where a virus is threatening to take over the entire world. And that part would absolutely be considered cyberpunk in any other context.
So what do you think? Is the inclusion of cyberspace enough to consider something to be cyberpunk?
Here's a trailer. I don't think it's streaming anywhere right now but if you get a chance, I think it's worth watching. Even if you don't consider it to be cyberpunk, it still has great animation and writing.
Also, if you enjoyed Summer Wars, the director made a similar movie called Belle. Belle is also a slice-of-life story in the real world with a monster attacking cyberspace. It's a different world entirely (not a sequel), just similar themes. And Belle is streaming on Max.
Summer Wars is amazing and a mandatory watch in my opinion. If you internet-seach the term aniwave, you can watch it right now (please equip pop-up blockers). Koi koi.
If your definition of cyberpunk includes Tron and Lawnmower Man, then yeah, Summer Wars qualifies, but in the classic sense, all three of the pieces listed are missing the "punk" part of cyberpunk, the dystopian setting. I think they have a common Transhumanism thread, enhancing the human condition through sophisticated technologies, but Summer Wars is the "shallowest" dive into the cyber world of the three. In the epic climax of the movie, Natsuki is playing Hanafuda against Love Machine on a flip phone, mega supercomputer in the background notwithstanding.