Well after 5 mins worth of text you finally see Doraemon (the blue cat). When he's in your house, talk to the lady there and you'll actually get him and the boy in on the platforming bit.
Y switches main control of Cat and boy. Cat has this gun that puts a little platform out (so you can reach higher places) boy has a gun. You shoot with X. After the boss the Cat gets a different level where steam shoots out of his head but I've not bothered to carry on playing out find out.
Game seems kinda nice but there's always an arseload of text to read. I may need to play more but to be honest I don't think it'll effect me either way.