I don’t know what counts as a long series with most people, but it’s only 333 chapters and anime?? what anime???
There are a ton~ of reasons why this is a really amazing series, and Shin and Sena’s sport rivalry is definitely one (like they pretty much have my favorite sports rivalry relationship ever).
Like, they’re always pushing each other to surpass their limits and to get better and faster and stronger, and yet there’s no animosity between them. Like, Shin’s blunt about Sena’s shortcomings, but he’s not purposefully mean or rude, while Sena literally thinks that Shin’s the best player, no matter who he’s playing. Even on the field, it’s super competitive, but not mean spirited.
Plus Shin only smiles like twice in the series, and both times have to do with Sena so…