Siliconera reports that both Wada and Kimura were no longer at Grasshopper as of some time last month, but the circumstances surrounding them leaving are unclear. Kimura was apparently considering leaving the game industry all together prior to joining Grasshopper.
Hopefully losing these two creators isn't a bad sign for Grasshopper, which is almost surely already feeling some pain from the poor sales of its great third person shooter, Shadows of the Damned.
{GameInformer}