Glad to hear that it worked. Thank you for your support <3 I'll check right away what's wrong with the stairs
So, I have tried myself and it works for me. This is what I did, could you confirm this is also what you have done?
--SPOILER AHEAD---
-I downloaded the second file
-I got all common dolls
-I took scissors and matches to kill the broken dolls and Okiku-san
-I got the yandere doll and sent him away by talking to him
-I got Mirror Helen
-I chose true end
-I watched the animation and opened the dolls' room following the order on the sticker
-I went upstairs and clicked on the red book
-I chose the option "I don't have any wish"
Then I went to check the stairs next to the Japanese door and the yandere doll was there.
Just in case, I'll create a new download link with the stairs unlocked so you can play it at least :)
I think I had previously made a mistake in choosing the other option instead of "I don't have any wish" and I think that was probably why I was not able to access the staircase on the right. I followed your points by redoing the true end and it worked out!! I'm so sorry you went through the trouble of creating a new download link and I'm so glad I can experience the full gameplay now :) Thank you dev for all your support!!! This is such a pretty and fun game!