is there any guide or something like a walktrough?
There's not really an "optimal route" or choices to maximize the content you see in one play through. Each of the girls will react to your choices, and if you show interest in being with them you will likely get some adult interactions. You cannot see all scenes in a single playthrough as there are mutually exclusive routes (i.e. sub vs dom) with each character, and some paths which will lock you out of other characters completely. A typical run through might only get 40-50% of the possible scenes, and some players have reported only getting to 90% even after several attempts. It's just a complex story.
While playing, as long as you make dialogue choices that correspond to the four traits (manly, cunning, sensitive and honorable) which are consistent with the "character" of MC you want to play, then you will get enough points to unlock the skills needed to see the relevant scenes.
If having to think about points is stressful or not interesting to you, then there are built in "cheats" to give double points, or unlimited points, so you will never have to be worried about your choice beingrestricted by unavailable skills.
Note that so far there are not really any downsides to "cheating" or having simultaneous relationships with multiple girls, but it seems like the consequence of being that sort of person will come to MC soon enough.
There are some specific routes with Kim that can be hard to get going, so I recommend you make a save at the start of the scene with her in a coffee shop before deciding how to proceed, there is a major branch in her relationship there.
Finally, there is an option to unlock the gallery scenes without having to play through if that is what you want.