Having a large cast of characters can be difficult. It is something that I think has hurt some otherwise great shows I have watched in the past like Baccano. I love that show dearly, but the cast is so large it is hard to keep straight for somebody on their first time through. Also, handling a large main cast is something that I think Naruto does very well (though they have a lot more time to build out the cast). I haven't heard too much about Seven Spellblades, so glad to hear they are doing this right.