In order to play this special version of the SUNKiSS<3DROP song, go to Sort ABC select D, select R, select O, select P, select S and play SUNKiSS<3DROP.
You'll play the jun side instead of the allison side (which is the default one). The step-chart is the same, but Junko Karashima will sing the lyrics, not Alison Wade.
To save your gave on Endless Mode, you first must clear 5 songs in a row. When the Results screen appears, press Select. When it says "Exit GAME MODE?" select Yes. Your progress will then be saved. To resume where you left off, select "Game Mode" from the main menu, when you choose your game mode choose "Endless". When the Difficulty Level menu comes up, choose your level then another menu pops up-here choose "Continue". You will restart after your last cleared stage-your score and progress will be preserved but your dance meter starts at normal (50%) and not where it was before. This can be a good cheat to keep going if your meter is dangerously low at the break point!