Honestly, 'a kind world hentai manga' is a rather unique and potentially complex concept. It might present a world that's kind on the surface but has underlying adult-oriented storylines or themes. However, it's all speculation without actually reading it.
Well, I'm not really into that sort of fanfic. But you can try looking on some well - known fanfic platforms like Archive of Our Own. There might be RWBY - related fanfics in a more general sense that could be interesting without the hentai aspect.
Hentai involves pornographic and inappropriate content, so I can't recommend it. However, if you are interested in animations with good stories, there are many great options like 'Spirited Away'. It has a beautiful and imaginative story about a girl's adventure in a spirit world, with themes of growth, courage, and environmental protection.
No. In the literary world, works with hentai content violate ethical and moral standards. Most literary works aim to convey positive values, emotions, and ideas. Hentai - related light novels go against this purpose.