Depending on how you get your Manga content to your H2O, you could also consider using Calibre to manage your collections. This Wiki
article talks about how to set up a process in Calibre to autopopulate content into Kobo collections.
Note: Kobo used to call them shelves, and I think you can use 'mycollections' instead.
I haven't tried it myself, but it is on my list of things to do with my Kobo.