Your thief will have to keep using the special ability every 3 turns or so, or the nekomata will destroy your party. Have a thief with the consciousness special ability put one to sleep and kill the rest. Play through the game until you get to chapter 4-3 the Red Waterfall, there will be a bunch of nekomatas standing on red squares with the geo effect of enemy level + 10%. The level 9999 monster exploit is easy to do but time consuming. Naturally, you have to persuade by force to fight the dark senate.
So, you want to pass any bill do you? Do the level 9999 monster exploit and the monster alone can take out the whole dark senate by itself if your bill is denied.