For comparison:
Nanatsu #7 sold 180,407 copies it's first week, a little less than Nisekoi. It's second week sales were 44,640 copies. Let's, for the sake of argument, say Nisekoi sold the exact same number of copies in it's second week. That would already put volume eleven at 242,792 copies, only another 57,208. That would only take a two or three more weeks to earn. It is doable. I chose Nanatsu #7 because it's first week sales were similar to Nisekoi #11. Because Nanatsu's sales were a little lower, it allowed for a more conservative estimate.