Yes, that specific variant happens if MC is a bottom. If you wanna just see it without having to replay the whole game, you can simply open it in the replay gallery, there you get prompted on which version you want to see.
The scenes you miss by following the in-game walkthrough are either story dependent or variant of scenes for situations in which you are not romancing every girl (for example, instead of a threesome with Emily and Alex you get a scene with only Alex or only Emily). The PDF walkthrough has a section with all the scenes and how to unlock them.
The 2nd scene is the flashback with Arisu. To unlock it you ned to choose "Reminisce" after her dialogue. The 3rd is the threesome with Alex and Emily, you need to be on both of their paths.
The android version does not have persistent saves, hence the existence of the chapter select screen upon starting a new game. I know it's not an elegant solution, but idk much about Android porting and that is the best I can do. :(
