Hey there! I have to agree with everyone else here that marketing is a big issue. I am constantly on the prowl for otome games or similar, so I found Heaven's Grave on itch.io pretty quick. But on the otome social media groups I follow, there was radio silence. Your games are well-written and a great price. They deserve to be doing well imo, so hearing they're not is a real shame. Another person you can ask to do a review (of either the demo or the game) is https://blerdyotome.com/. They're fairly active and have pretty reasonable reviews.
I understand the lack of media presence. I'm not very into social media myself, so I get your reasons. Unfortunately when it comes to commercial games, social media is life blood. Especially in this environment. I've been into otome games for a long time (15 years give or take) and there's been a huge shift in content between then and now. A lot of indies are interested in doing VNs now. And while the audience has certainly grown, I feel the market has outpaced it. If you do a kickstarter, please do this-check when other otome-like games are running theirs. I've seen promising kickstarters fail not because they were bad necessarily, but because multiple otome games were running at the same time. People with limited money are forced to pick and choose between games they may have supported at another time.
Kickstarter in general has also shifted...I've been supporting otome games for a long time (will support yours when/if you do it) and I feel people used to support more in the past. This was partly due to the lack of any otome games whatsoever, but also because Kickstarter was brand new, and had people's trust. However, people using it to scam others out of their money, never delivering what they promised, or giving out refunds, has shattered that trust. People are very wary now. I hate telling you this because I don't think there is much you can do about the current state of affairs, but I think the one thing you can do is talk about your previous games. If you do the Best Friends Forever kickstarter, link your other finished games, talk about them, show potential backers you have delivered in the past. That gamedev isn't a new field for you-you're reliable. It's great press not only for BFF, but your past works as well. Oh, and of course, have a demo. I can't remember where at the moment, but there was a survey/study people did that showed kickstarters with demos did a lot better than those that did not.
Another option I've noticed some indie VN devs do is Patreon. I believe Royal Alchemist does it as well as Fablesoft. I don't think this will get you a lot of money, but any is better than none.
As you are alone, you need to add marketing into your work time. Marketing and word of mouth takes time and that needs to be added into your game release estimate. If you Kickstart, be fairly active in updating your funders-monthly would be ideal. Even if you don't feel like you have any updates to give. People just want communication. If it helps, make a little percentage progress graphic with things like writing, editing, backgrounds, etc. Even if you don't have a lot of progress to report, just seeing the writing bar change from 55% to 60% helps both you and the backers realize work got done.
Another Kickstarter suggestion is to mix up the pricing of your tiers. Do not be afraid to have a couple really big, costly tiers ($200+) with a lot of smaller ones. I've seen Kickstarters where the max cost tier was $ 60. The Kickstarter would then fail because people would refuse to give more. There are big funders out there, but they won't give more unless there is a clearly stated option to. They must feel like they're getting their money's worth even if in reality, the product to cost ratio is much more favorable to you (like an extra character they designed getting added to the game, with all the other previous tiers rewards). If you say a tier reward is $60, it's $60 dollars. That's it's declared value. Some kind backers may give up to $75, maybe even $80 for it, but beyond that? People's lizard brains kick in. They get stingy. They start to realize how much they're actually giving and rationalize that it's not worth it.
Have 1 dollar tiers! A lot of people use 1 dollar tiers as little reminders to update their pledge, and again, some money is better than none. Usually these tiers are thank you notes or names in the credits...Basically, just have a lot of tier options. The more, the better. Some people may want an artbook but not key chains, or two itch.io keys instead of one, etc.
As someone else said on here, talk/follow other VN devs. I can't say if there are deeper issues, as I am not a game dev, but on the surface at least, VN game devs really want to help each other. Over time they post snippets of their own financial situations, of what helped them and what didn't, game resources, advice for fellow indies, etc. One such person I'd follow is Winter Wolves dev. They are very honest about what works for them and what doesn't, have info on the ins and outs of Steam (lemme just say-your failure on Steam is likely not your fault, the algorithm has changed and fucked with A LOT of indies sales, even more prominent ones), and have been here since the beginning of the VN scene. While I wouldn't take all their advice as gospel (we have different definitions of what good writing is, haha) they are a font of knowledge on the business side of game dev. Check out all their social media, such as their wordpress too.
Further, tap into their playerbase! Host other people's indie games on your site! Have them host your game on theirs! Encourage each other. Having a central "hub" outside of itch.io would help with that and marketing.
I'm sure I have more advice to give, but my brain's blank at the moment. If I remember anything further, I'll drop it in. I hope you were able to find this useful.