Kaburagi Karate in action.
The karate style, Kaburagi-ryu'- a fictional martial art based for kumite (組手) on Kyokushin (極真会) but has katas (型) that belong to other styles such as Goju Ryu (剛柔流) or Shito Ryu (糸東流), an example is they practice Suparinpei (壱百零八) as seen in the chapter'The Melancholy of Hayama'. The style also incorporates the oldest styles of karate, that includes Tōde/Tō-te (唐手, Tuudii, translating as "hand of China") and it's descendant styles: Shuri-te, Naha-te and Tomari-te.
Kaburagi-ryu, is a full contact traditional combat style created by Kaburagi Juuzou, it's very first president. Then the second president, Kaburagi Shigemi, is none other than Kaburagi Juuzou's second son.
The colors for each kyū, (rank before a dan/black belt) in Kaburagi-ryu karate.
There are only four schools in all Japan that have Kaburagi-ryu karate clubs: Reinan University and Bubudai University are two of them reported in the manga.