So I've read every single guide I could find on the internet about this Achievment after trying them all out I will just write easy steps to follow to get the achievement

1. Start Hanzo Mission 5-5
2. Pick a charakter between lvl 30-40 so you take enough damage
3. Beat the enemy up until they are in Shinobi mode with only underwear left, but dont get their healthbar to red (below 30%)
4. Get yourself beaten up until you have about 20-30% health left and are in underwear nothing else left
5. Carefully punch the enemy until their healthbar is red (their picture should start to blush)
6. After the next 2-3 hits you take they should user their Absolute-Secret Ninja Skill and finish you off

The problem I had with the other guides about this achievement was that they didn't tell you to use a character with a low enough level or to go berserk to strip yourself which prevented me from getting completely stripped by the Absolute-Secret Ninja Skill from the enemy I'am pretty sure that is a bug

Footnote:
English isn't my native language so please if I made some bad grammatical hiccup that should be fixed contact me

Thanks for reading!