BIGNET ... (don't know this one -- maybe something about stage numbers?)
I'm not sure either, but I'm thinking めんとばし might be 面飛ばし. Something like "to blow away the mask" (take it right off) or to "launch the mask" (throw?) EDIT: I assumed this was "mask" but it could be face as well considering the following.
EDIT: I did a little searching, and I could only find this in the search result text. Not on the page it referenced, nor its cached version.
". Battle Fantasy ... Register as "BIGNET" with a name entry that easily defeats enemies. Then start the game with operation BHA and select "BIGNET" by name select. Now you can defeat the enemy by pressing the start of the 2P pad during play. ○ Another logo appeared When you turn on the power and the SEGA logo appears, press and hold up, start, A and C. Then, the big net logo appears instead of the micronet logo. ○ Register "MUTEKI" as an unbeatable name entry and play the game with Operation BHA ..."