Maybe under the filtering you can be able to filter out web comics and novels for the straight manga lover

Since there is a category for web comics, you can filter them out when you do an advanced search by putting the category name, "Webcomic," with a minus sign before it in the category filter box. Light novels can be filtered out by choosing the "only show results for manga" option (although this will filter out all other media types too).

Manga Cover Database