can u talk step by step to get tentacle suit?
At the start go through the old route and save the woman from goblins to get the Mayari rescue flag if you haven't already(certain flags seem to work regardless of what run you got it on) once you reach Pampas Grass pick
++Observe People (097)
++Keep watching the row of slaves(108)
++Attack and rescue the girl(111)
++Then suddenly, I heard a voice[Mayari's rescue flag](115)
Then drink or don't the teas Mayari gives(you'll get a nice ending as Mayari's experiment if you fail a drinking check so either have the Judgment Roll [Success] or just refuse them all and Listen to the Story(157) once she stops offering tea to avoid that).
++Have a chat with Mayari(163)
pick ++Super bio armors(164) and ++Wear(172) for the scene where you try it on but after you pass out she removes it and gives it to one of her henchmen.
Then in the arena you can either fight, watch or help Surval(if you got her flag as Cerot I think), helping Surval and then failing at trespassing alone is one of the many ways to get to certain being a slave route that lets you save Cerot and yourself from wearing a tentacle suit it's pretty long but if you end up in the arena when an attack happens pick ++Search for Cerot(978) or if you end up escaping without being in the arena pick ++Prioritize Cerot(988) either way after that you should get ++Leave this place(1015) (Should actually be the other option but the options are bugged and link to opposite choices), pass a check, fight and then your clothes change to tentacle suit for a bit(forgot that in that scene it worked) before you get a scene of you and Cerot removing them and then Cerot remembering how she got hers.
If you don't help Surval in the arena you'll soon get the option to pick how you want to try to rescue Cerot with Mayari's help and picking ++The Resistance flag(189) lets you get to the cg less scene I already mentioned where the clothes didn't change automatically for me despite text making it clear you're wearing one.
Not sure if you can get to helping Mayari even if you don't get her to help you at the entrance.