Well, I'd love to give you some real critique, so let me try:
-There are major anatomy flaws, specially with eye placement and hands.
One good trick to point them out is to mirror the page, and you'll see how odd they are.
-Using Japanese characters for sound effects when the manga is originally written in English makes no sense.
I know this is your decision, but I'd strongly suggest you to use English characters for sound effects as well.
-If you're targeting western audiences, you should be using the western reading format of left to right (unless you plan to publish the manga to an eastern audience).
-I can't really comment on the characters personalities since it's too short for me to do that, but their designs are nice.