This game has hidden developer credits.
The FamicomBox is a display unit console primarily used in Japan. It can have multiple games loaded in, plus an optional coin box and a timer. Strangely, while it uses Japanese games, everything is NES-themed!
Turn the key on the FamicomBox front panel all the way to the left. When the "GAME TITLE & COUNT DISP." screen is displayed, press Up, Down, Left, Right, A, B, Select, Start on Controller 1.
The screen will scroll up, and instead of the menu a screen reading "NINTENDO ENTERTAINMENT SYSTEM (FAMICOMBOX) DEVELOPMENT..STAFF" will appear. Now, press Select to cycle through the staff members.
A hidden copyright is present inside the ROM, along with build dates:
THIS PROGRAM IS MADE BY TOSHIO SENGOKU. MAKE START 1986/08/27 - MAKE END 1986/09/10.