@zing
I don't know if you're definition is wrong but in my opinion a serie is ecchi when there enough sexual content for it to not be just a little fan service (for exemple Infinite Dendrogram one and only bath scene doesn’t make it ecchi) but it's still tame enough to not be erotic (Jk harue) or hentai (probably better to not give exemple).
Sorry i don't really want to re-download and re-read the whole thing but if i describe it you will probably remember, it should be around the end of what is vol 2 of the LN. It's when Van is still in the gouhl village and is helping with the fertility problem, he use his skill phantom hand to go into the gouhl vigina just after they have sex and make sure the egg is fertilise and put it in a place where it wont "fall", if i'm not mistaken the fertility coming from the egg being loosy attach.