The Aliens Are Here. But Why Are They Here?

Before We Vanish starring Masami Nagasawa

Three aliens come to Earth and take over human bodies to prepare the way for an invasion.

I have to say that I found this movie interesting to watch but I can't say that it was good.  First off, it was very slow and meandering.  A lot of things happen that don't seem to go anywhere, and a lot of things happen that don't seem to make sense.  It's an interesting idea to explore what happens when someone loses a key concept.  When a workaholic loses the concept of work, does that diminish him or free him?  But i never understood why the aliens were collecting concepts.  Or why these three aliens had to come to Earth before the invasion.  Or why one fit in his human host just fine while one couldn't figure out how to use his human legs.  Or why they needed to build a communication device.  Or why they were doing anything they were doing.  The plot didn't feel cohesive to me.  So, if you have two hours to kill there are worse ways to spend it, but I could think of better ways to spend it too.