I tend to not be too crazy about manga style drawing most of the time, but these are good. Your characters have a lot of personality. I think you could benefit from doing some hand studies though, because in a bunch of your drawings the fingers look kind of crooked or the palms are stiff. This is mostly a foreshortening issue; if you wireframe the whole hand before you do your final render you shouldn't have this issue. Try scribbling a few sketches of skeleton hands and muscle structure in various poses in your free time. Some medical websites can give you good reference.
Also, that is a minor critique. Your art is good. I just like to try and always leave something an artist can do to improve themselves.