nice
the jp grammar is good, though, in some scenes, pen-kun's voice sounds soft even though he is supposed to be angry, and sometimes you sound like a real jap dude speaking, which, i thought was cool.
by judging the dialect....hmm...i am not japanese but i think you used the casual dialect....cant remember what its called...but anyway, why not try some other dialects to differ the 3 main characters from each other? for example, osaka-ben or hiroshima-ben?
all in all, this is a good cartoon, the voice acting can do a bit more practice
i rate it 9/10 and 5/5