When I add my favorite web comic (Webtoon), it shows all episodes of my webtoons.
If you've already seen some episodes, you can long-click on them to select and mark them as read.
When you watch the episodes you had, remember that Marktoon has read them and delete them from your list of episodes.

Main functions:
-Add favorite webtoons
-View webtoons in series from episodes I haven't read
-Mark previously read episodes as read

Support webtoons:
-Webtoons.com

Access
[Required access rights]
-Displayed on top of other apps: Use to display menus such as navigation and exit reading the episode while viewing episodes on webtoons with a browser