For chapter 1 - poss spoilers here and all the chapters below:

1. You need to get the nail brush 1st - awesome fellow Steam player Battler Ushiromiya found you can get the nail brush also from the monokuma machine but if you want the extra scene without having to go backwards then here is what to do:
2. Talk to the Ultimate Cosplayer Tsumugi the morning after the failed attempt and click yes as an option when you talk, even if it seems like a weird question please just say yes.
3. When you get to the free play event, you can chat to someone or rest in your room and ... you will then go on to a nice pedicure scene not just with her cuteness with a sexy hunk who sadly will shortly be murdered. Please save the game before you talk to Tsumugi to ensure everything goes well xxx

Screenshots for a taster are below in the spoler tag below :) Very cute

For Chapter 2
An enormous thank you to Nagito Komaeda for helping me find the 2nd of the hidden cutscenes in Chapter

1st hidden cut scene -
1. When you can, buy in the school store the parasol
2. After you have put in the mysterious objects i and explored all the new areas, meet Angie who wants us to go to the gym, chat to Tenshi Chabashira (Ultimate Aikido Practitioner) in the school entrance :) Then go meet in free time in the afternoon because ... Under the parasol our Ultimate Magician, Ultimate Artist & the Ultimate Aikedo Fighter are in their swim suits getting the VIP treatment from the Ultimate Maid! :)

My goodness, the cut scenes are so sexy in this 1!!!!

2nd hidden cut scene:
1. Have the medals which comemorate the opening of the casino
2. The morning after the free time events, talk to The Ultimate Inventor and away you go! ;) the Ultimate Astromaut goes for broke in the Casino :Dv

Screen shots for both scenes are here XD

Sexy screen shots below in the spoiler tag:




Here is a screen shot - not sexy but made me giggle in sympathy ...

Spanky Pie has at great speed found out the scene you can un ock in Chapters 3 & 4 :) Thanks hero!

For Chapter 3
1. you can unlock a scene if you have a gun of man's passion.
2. You can unlock it by talking with Himiko in the courtyard. It's pretty much pure fanservice. Ha ha!

For Chapter 4 - There are 2 scenes

One with Himiko again when you have a Dark Belt and you will train together in the dojo.
The second one is with Kaito if you have a Pure White Practice Sword and you will have special training in the courtyard.

Also if you have the key of love from the casino you can get a special scene with seemingly random people every night. You will get waken up by Monokuma and then if you still have more in your inventory the game will ask you every night if you want to use it.