Bathhouse key not working on bath #11

[RedFoo]

I've gone back to every floor in the bath house and every floor in yukiko's castle, nothing is working. I fought the optional boss on the last floor of the castle as well. It says the door is locked by "strong power". I've tried to use the key manually on the items screen, but nothing happens. I have uninstalled and reinstalled as well. Has anyone come across this issue? I've been having this issue for months, I stopped playing the game hoping it was a bug and had been fixed by now. That wasn't the case lol

[Nerrinas]

Assuming you've saved Kanji, are you going back at the right time? The optional boss for the bathhouse is available from June 7th onwards.

[Invenblocker]

Do you mean you're returning to the bath house after having saved Kanji, or are you having trouble accessing the Shadow Kanji boss battle?