how to unlock this scene
You have to free the old man(Sasuke) but choose to not use Provocation on him, if you use Provocation on him, (spoiler) the story cuts short with Kamika ending both the old man and you bc you chose to go against her, just freeing him without using Provocation on him means she only kills the old man.
Not saying cause ion wanna spoil it for anyone else who may wanna check the comments for tips, but I will say that you'll unlock Ending #6, of which imo is the best ending, at least for what we have so far in the Itchio version of the game.
Oh, also, make sure when you're on your date with Hinata, you go down the Love Route, the Itch version allows you to watch some of the Patreon scenes for her, which helps build the Love Route bar.
If it's still not working then you must be doing something wrong, are you heading down the Mirai path instead of the Hinata and Sakura path? If not then you need to.
If that's still not working for you, then make sure your game is up to date, and if that doesn't work, then you must have a b bugged game, and need a reset. If THAT doesn't work for u, then idk, message the maker, they'll probably let you know what it doing wrong.