I don't think that's off-topic either. It's a fair question.
So, not exactly inspired or borrowed from Yandere Simulator specifically. It's more of coincidence and common themes. The premise of my story was to be about queer polyamorous yandere's that fall in love with each other. It also involves demon(s) and god(s) as part of the main plot. Yandere simulator is about one yandere in love with a totally normal person and has love rivals that she needs to eliminate. I've had a love and obsession for the Yandere genre for a long time, and I knew that creating a game that involves yandere's would definitely bring people to link it to Yandere Sim, but I swear that most of my influences did not come from it, even if I do enjoy it.
The uniforms I designed is actually not like any of the uniforms from Yandere Sim (as the sailor fuku style that I use is black and white, and his is navy blue and white) and happens to be my original design based off real high school uniforms from Japan. In fact, my character Chiaki, who was created before TICL is what I decided to go with for the uniforms.
I suppose it might seem like Sakiko's fashion is similar to Oka, but that is because they're both Japanese gothic high schoolers. Though I admit, I didn't think about the fact that they both have spider print gloves and tights, but spiders are an important part of her character, which is evident through the nickname that the Demon uses. And if we want to talk about personality (I know you didn't mention this, but I thought I'd add it just in case), Oka is shy whilst Sakiko is completely apathetic. Occult Club is uncommon, but it is a thing in some anime. I felt that it was a good fit for a club of goths. To be honest, most, if not all of the fashion in this game is inspired by actual clothes. I just altered little details such as colors with them.
(This is not at all saying that Yandere Dev hasn't either, I'm just say that I have not looked to him or his game for reference) I've spent a lot of times doing my own research of the actual lifestyle in Japan. I researched the lives of Japanese adolescents and how school works there and even made a chart for the classes each student has even though it'd never be seen by the audience. I even made a calendar with when the school days, breaks, and trimesters are and when they have uniform changes, as well as their holidays.
If we also want to bring Yoko into this, being a Yanki/Delinquent, I created her before Yandere Sim implemented the delinquents and her main inspirations are actually from Kamikaze Girls and Fruits Basket.
I suppose I can't say it's even coincidence, it's just that we are writing about similar topics in very similar settings, so there are definitely bound to be common territory. I know this early access just came out a couple weeks ago, but I've been working on the project for a couple of years and had the idea for it for even longer. I also intentionally put some tropes that might also be in Yan Sim as a jab at anime, and this will be especially prominent when Yan is introduced as a key character (he makes fun of the hair colors and other things like that).