Sound test
On the title screen, press [Start while holding top left + Select + A + B] to proceed to the sound test. Select the song number with left and right, press B to play, press A to stop, and press the start button to return to the title screen. Also, the specifications change depending on how many times you enter the command on the title screen, and there are 3 types in the order of [Ryu -> Irene -> Both] (Example: Wait a few seconds on the title screen, and when the Tecmo logo appears, press start to enter the second title.) Display the screen and enter the command to enter Irene mode). In addition, in the mode where both Ryu and Irene appear, you can listen to sound effects in addition to the song, the song title is also displayed, and it is a deluxe version that also displays audio waveforms for 5 channels.
Bonus visual
At the end of the ending, when "THE END" is displayed, press [Right + Select + B] and the Evil Demon King and Ashtar will laugh. (This itself has no particular meaning. It is unclear what the intention is)
