Edit: I'm no longer accepting any more votes and already have the second book on the way!! A preview of the book will come out soon enough.
Ok so, I'll try and make this as short as possible. I just want you guys to pick the next book I'll be doing since I'm also having a hard time choosing, I also wanted to do a little 50k view special.
This current book only has 50 chapters and hasn't gotten an update since. I'll still be updating this one until chapter 50 and if there's an update I'll update.
Some of these I've read just a bit and some I haven't had the chance to read. The deadline is until I've reached chapter 50 for this book. [I lied]
Here are some of the books and rough idea.
Demon Slayer X Genshin Impact. - Furina's the MC and there's no romance. Timeline takes place before Yoriichi was even born. I haven't read this one yet.
One Piece x Genshin Impact - Furina's MC again and there's also no romance. Timeline takes place when luffy got his straw-hat. I got up to chapter 20 so far.
Genshin Impact - Sandrone X Columbina. There's romance and no harem. Sandrone is MC and goes back in time way before the plot of Genshin. I've only gotten up to chapter 2.
Genshin Impact - Furina X Male!OC. There's romance and no harem. Male!OC is the MC and it takes place around 4.0? It's very romance theme. I haven't had the chance to read it yet.
Genshin Impact - Furina x Furina!OC. Romance (slow-burn?) and no harem, basically selfcest. Furina!OC is the MC and takes place 500 years before cannon. If you read Genshin Impact: Transmigrated as Furina's Second Personality, then it's a similar concept. I've only read up to chapter 20.
Pokémon X Genshin Impact - Male!OC is the MC and there's no romance? Timeline is the start of Genshin plot. I've read up to around 50-70 and it's been a real long time since then.
That's all the books so far. I'll drop the links to each of them. There was a naruto one I was going to add but i feel like my list is getting too long.