The inspiration for why Shokaku and Zuikaku hate their Senpais, Especially Kaga, comes from historical facts. Shokaku was built with the specifications to be better than Kaga, and faster than Hiryu. And Shokaku managed to not live up to any of those expectations. She had less capacity than Kaga, less survivable than Kaga, less armed than Kaga, and while faster than Kaga, she was still slower than Hiryu.