Honda beat Kawasaki to it. But only by a whisker. In the late 60s both companies were working on a 750cc bike to satisfy demand for more power and lure riders away from European bikes with larger capacities.
Honda was first, with their CB750, which caused Kawasaki to completely rethink their own project. The result was 900cc to beat Honda's 750 along with styling and road presence to match.
See the story on youtube: www.youtube.com/watch?v=YW4_YZ3Skh0