Tantei Opera Milky Holmes spends a good part of its final episode
focusing on the battle against Arsene as she cultivated quite the little
setup in the previous episode in order to make sure the girls go up
against her with their minds in the right place. After failing their
tests and then going off to work elsewhere since they couldn't be in the
school anymore, Arsene has managed to tweak them all enough to get them
to band back together and remember what it was that made them such good
friends. With the belief that Henriette is in her grasp, rather than
Arsene being her through illusion, she's created quite the little event
that's being broadcast around the country that's inspiring others toward
being a detective.
The final battle between the two side sis unlike anything we've seen in the series to date as it goes big, a bit too big in how it's presenting itself at times, but big in a way that really makes you feel like this is something epically important. The action, choreography and animation itself is really quite good here as Arsene's various attacks through illusion moves everything up several notches. But it also goes in a very fanservice oriented way when Sherlock essentially motorboats into Arsene's chest and realizes from past experiences that she's actually Henriette. Arsene tries to carry off the trick for a little longer until she realizes it's not going to work and performs the equivalent of a colony drop on the girls so that she can get away from it all.