- Have a first save at the beginning of chapter 3-3;
- Made a backup copy of that save in another slot;
- Witnessed the scene where the Oni girl blows up herself;
- Loaded the backup save and went to chapter 2-1, bought this thing from Oni Girl
Its price was 1000, I supposed it was the item needed (also tried to have a look at the accessories she had on sale, but game crashed when I did that);
- Loaded my original save of chapter 3-3, that item appeared among the ones in the "gift tab" (I'm doing some guesswork here) and I triggered the scene with the Snake Girl;
- Oni girl still interrupted funny times and proceeded to blow herself up. Shouldn't I have a fight with the Snake Girl at this point? The only thing I can think of is that I bought the wrong item, but it was the only one sold at that price.