- Would they ask for a take down for any other reason, when various other manga reader websites are making money off them?
Merely looking at the fact that the other sites have not been taken down is not a good metric to decide if you will face an infringement suit for your own site. Consider the following possibilities:
The manga on those sites may be published by a different publisher than the manga you want to host, and that publisher of your desired manga is more litigious.
The manga publisher may not have been actively pursuing infringement for the last several years, but they may suddenly decide this fiscal year it's a financially good idea to start aggressively pursuing infringement. They will go after the other sites and your site at the same time.
Because you plan to give them money, you are actively drawing attention to your infringing site. While they may not find it worth their while to seek out whatever new infringing sites pop up every week, in this case, they don't have to come looking for you. You show up to them, actively telling them that you're infringing their copyright.
Of course, they might not care. They might love your idea. Regardless, the legally sound way to do this is to ask for permission before you do it, rather than forgiveness afterward. If you don't, you are certainly vulnerable to a lawsuit (whether or not the publisher will pursue the opportunity to sue you is a question left to the discretion of the publisher).
- Considering that myself is not going to be making any money off their work, does this still fall into the category of criminal act? If so, are there more than take down notices that can happen? (C&D? financial punishment? imprisoning?)
Having your infringing site taken down is the minimum that could happen. If you commit copyright infringement, the copyright holder is fully entitled to file a lawsuit against you at once. It's possible that they could just file a DMCA takedown notice to your ISP to have the content taken down, but they are entitled to sue you for damages as well.
Maybe they won't sue you because it's not worth their while. If not: lucky you! So, ask yourself: do you feel lucky?
Copyright infringement is typically a civil offense and only punished with fines. It can only qualify as a criminal offense under 17 U.S.C. §506 when the infringement is "willful" and meets one of the following criteria:
(A) for purposes of commercial advantage or private financial gain;
(B) by the reproduction or distribution, including by electronic means, during any 180-day period, of 1 or more copies or phonorecords of 1 or more copyrighted works, which have a total retail value of more than $1,000; or
(C) by the distribution of a work being prepared for commercial distribution, by making it available on a computer network accessible to members of the public, if such person knew or should have known that the work was intended for commercial distribution.
As long as you don't violate any of those conditions, your infringement is not criminal. Condition B seems most likely, if I am reading it correctly: if your site serves a $10 book one hundred times, then you've met the $1000 threshold. The threshold of what makes an infringement "willful" versus "ordinary" is somewhat nebulous; see Wikipedia's article on Criminal Copyright Law in the United States.