https://www.dlsite.com/maniax/work/=/product_id/RJ365031.html

@kono1887 link was taken down due to DMCA (images for the game were from an anime & game series, the maker didn't have rights to them)

It's not just the link, the game sales were halted completely as far as I can tell. Were they outright taking original materials as they were from the original source, or were they similarly to many others just using their IP? Regardless of which case it was, they either overstepped how blatant they were about the references, made poor decisions regarding marketing or just got "unlucky" - such as releasing around a time when the developer was more vigilant (or looking for someone to make an example of). In general you'll find that doujin creators will almost always either replace a single character in a franchise and/or character(s) name (with a different letter or just an asterisk), alternatively just use an obvious reference or pun as a replacement name. I have noticed that for the mobile game developers in particular it's rare you ever see any titles floating around with identical names - I assume they might be more vigilant about their IPs than the average JP company (note: in *general*, not always). Mind you, this is just based on my loose knowledge about the copyrights within the doujin scene and anecdotal evidence - take it as you will. I didn't do much more research than a quick search and reading the homepage for the circle. Thankfully the game was at least grabbed by enough people to end up here before it got taken down - would've been a shame if it ended up just lost in the void.

Splush Wave has been making games exactly like this since 1998, and to my knowledge this is the first time they've ever had to take down a game. I won't assume whether they did or did not actually plagiarize anything; they haven't released an official statement on the matter anywhere I've been able to find yet. I will say they've been drawing or commissioning their own art for 24 years straight and I have no reason to believe they'd suddenly stop. In my opinion the most likely scenario by far is that Cygames has a very thin skin and issued an obnoxious lawsuit. As I said I have no proof but that circumstance seems by far the most plausible to me. In any case, this and all other versions of the game on Nyaa appear to be out of date. The current version as near as I can tell is 1.03. The difference between v1.00 and v1.03 is pretty big; the updates not only fix some major bugs, they add an entire new 4 player game mode. This update has currently been scrubbed from Splush Wave's website along with all other mentions of the game, but it was saved to the Wayback Machine by an organization named "Archive Team" and a different anonymous person who just hit the "Save Page Now" button. Big thanks to them, they've preserved a small piece of video game history. Here's the Wayback Machine link: https://web.archive.org/web/20220226114058/http://splushwave.com/ Click on the ダウンロード button on the left, then click on the link that says "ま～じゃんコネクト！修正パッチ　Ver1.03" to download the patch. Also, thanks to everyone who pirated this game and shared it. I'm sure Splush Wave would prefer to be paid for their work but I also bet they're glad it still exists and people can still enjoy it, thanks in part to pirates like you. Situations like this are the best possible argument for peer-to-peer file sharing I can imagine.

I mean, considering they made a hentai game with Fate/Grand Order characters, that's probably one of the reasons they got taken down.