Hello, Liseria! You need to push the two rocks to the holes (after you move one, another will appear) to make bridges downstairs. It's a puzzle! :p
OMG! I didn’t notice that you had answered my reply! Sorry about that. At this moment, I’m not thinking about making a continuation because I’m working on my next game named Agent Lovesdick. As you really enjoy Yuki’s, I suggest you follow Male Doll's Itch.io page because in early June I'll release Agent's demo for a test! Stay tuned and thank you for feedback.