Great manga, that is so unfortunate it is not well known.
The Doraemon inspiration is pretty obvious and the author doesn't hesitate to play with it. Beginning as a pretty simple comedy with a young Honmaru, it gets more mature and serious when the protagonist grows during the story. You got funny moments, fights, rivalry, friendship, love, etc, in short, everything that makes a good nekketsu.
The fan service is really present but is well integrated.
If I had to describe this manga shortly, it's a big mashup of Kimengumi, Doreamon and sport nekketsu.
P.S.: Sorry if my sentences don't make sense, my English is kinda poor.