This is a good question, one that only raises a few biblical references in my mind.
But what it all really boils down to is that you are asking man and not GOD himself. I personally do not know what is in the content of the comic book you are talking about, and unless you were my child, I couldn't very well tell you if it was bad or not (Not that my child would listen to me, because they don't always do that), but I know if you pray about it that HE will tell you what is and is not permissible.
I do want to post one biblical scriptural reference however, and I only think it is realavent to the amount of time we do things that take away from what would be better for us by getting into the word of GOD, prayer, helping out a neighbour/family member, etc... instead of popping in that video or reading non fiction, etc....
2 Timothy 3:1-5 But mark this: There will be terrible times in the last days. People will be lovers of themselves, lovers of money, boastful, proud, abusive, disobedient to their parents, ungrateful, unholy, without love, unforgiving, slanderous, without self-control, brutal, not lovers of the good, treacherous, rash, conceited, lovers of pleasure rather than lovers of God-- having a form of godliness but denying its power. Have nothing to do with them.
Ask yourself If Jesus were here would HE approve of me watching or reading this material? Will what I am about to do Glorify GOD? I think if we were to ask ourselves this on a regular basis when we are bored and have nothing better to do with our time, that we may just start making better choices of what to do in our spare time and do more of what is right in GOD's Eye's.