I appreciate this story. DDLC stories are not only rare, but the main characters of these stories are either obsessed with saving the girls, or they are shy and meek and always get led around Monika. So it is quite refreshing to see a story like this with a MC that actively flirts with the girls and isn't a stuttering virgin.
The premise is also great, not being restricted to the DDLC universe and having the potential ability to travel to other game worlds... Well, it is certainly great that this is a harem, because let's be honest, having access to a multitude of universe and not taking advantage of that and forming a harem would just be... stupid.
The only thing I hope for is for the characters to actually have romantic development, and not just get collected by the MC like pokemon. But this is something that until now, hasn't been a problem, and I can see that the author is certainly not going down this path, so there is no need to be worried about this aspect
The only complain I have is the update stability. Writing fiction is hard, I would know, but it's a bit frustrating to have a chapter every two days, and then suddenly, weeks pass without a single chapter.
Author, my advice to you would be to upload a chapter a week. It would allow you to have a more stable schedule, and it would also give you more time to write, or review chapters. You can tweak it around as you see fit, but if you can't write consistently, just keep some chapters in stock, and hold on to them, just in case.
I don't know your situation, do with that advice as you'd like, but always remember that having a stable update schedule is important. Of course, it is your own work, so no pressure here, I just hope helps you, as I certainly want to read more of this story that you have created