That Time I Got Reincarnated as a Slime, Vol. 14 (light novel)

Having easily thwarted the Eastern Empire's invasion, Rimuru wishes to end the
conflict once and for all and therefore heads for the imperial capital to take out the
source. Meanwhile, Yuuki has worked his way up inside the Empire with the intention to
stage a coup d'état and usurp the throne. Rimuru, however, comes to find that the
Empire's true power is on a whole other level from what he’s seen so far...