There are very few more realistic VN/Games revolving around BDSM as a consensual fetish, so the basic idea sounds a little more unique then most BDSM style VN/Games already being developed and/or completed... That being said, are you going for a traditional Visual Novel style, a grinder, or a hybrid? Based on your example visuals I almost get a sense that you want to add either a 3rd person shooter vibe or VR?
I really don't see a 3rd person or VR style game working all that well, plus it is FAR more intensive to create... Add to that, the number of people actually even owning VR equipment is actually very low, so you would be pushing your project into a corner with very few players/readers... Steam keeps trying to push VR games, but it's a highly small niche market of gamers, on top of that, most are rather simplistic looking and no where near the quality of other more traditional PC games...
Outside of all that, if your going a more traditional VN/Game route with a good story, here is what I recommend:
1 - Determine what 3D Imaging Software you want to use based on your skill/talent with using said software.
2 - Determine what Engine you want to use, such as Ren'py, Unity, etc...
3 - If you have a story in mind, then sit down and work on an Outline of the story to include any side stories and plots, from the beginning of the story to the end and/or ends... You need to include any choice branches and so on... By doing a basic outline, which can be as detailed or undetailed as you want, of the whole thing you can help ensure continuity and flow prior to designing the more detailed parts of the story... You can also design personality traits for the characters when doing an outline as well...
4 - From the outline you can begin writing the more detailed bits of the story... This is where the normal story telling is made along with dialogue and monologue...
5 - Design quick hand drawn story board sketches so you can plan out the visuals prior to doing the hard work of making the visuals... That way you can pre-plan camera angles, stances, body language, event scenes, etc... The reason why this helps, is because then you can work out the sequences of how the story will play out, along side plans for the visuals, ahead of time... Which will then help you determine what works and what doesn't when playing out the sequence of events and story, prior to doing the hard work of creating the visuals...
6 - Do the hard stuff like making the visuals, designing the coding within the engine, adding everything together, play testing, etc...
By planning everything out in advance you can work out kinks in the flow, story bits that do or don't fit, plot issues, and you may even spark more imaginative ideas as you work through it, even post planning... Planning and prepping is a stepping stone... You see it in movie production, tv show production, and even some book authors use outlines... If you just wing it, there are inherent flaws that can crop up, that you may or may not even see right away...
Anyone can sit down and come up with ideas for a VN/Game, and get excited at the prospect... But when it comes to the meat and potatoes of development... It's not all fun and games... It can be tedious sometimes... It is HIGHLY time consuming... May require a heavy monetary investment, either right up front, or over the long haul... Depending on your choice to make the content from scratch, or to buy pre-generated models and so on... Even more so, if you pay others to do some of the work, and even then you don't always know if your gonna get your moneys worth... Then there is also the possibility that your hardware needs upgrading... Depending on your skill, experience, and/or talent as a developer, will the product be any good and/or will the general public like it or not... So you have the possibility of having to deal with negative responses, and depending on how mature you are with dealing with it... Will you become discouraged, or will you just take the input as is and learn from it, or ignore it, or will you embarrass yourself with defensive public outcry... So many other things as well... I'm not trying to discourage you from making your product, but I just want to help ensure you know exactly what your getting into... Being a developer is not easy, and being a good developer is even harder...
Zip