Board Thread:General Discussion/@comment-24189673-20131120064700/@comment-26091912-20151106001534

Shoshiki wrote: ALRIGHT YOU GUYS LET'S TALK ABOUT THIS NEW CHAPTER, YES? ALRIGHTY! I think Nanao's mom is Lisa (The resemblance is too striking for it to be any kind of coincidence)

Yeah, because they both totally have the same surname. (Honestly, though, it wouldn't surprise if it were true; especially with everything that's been revealed, so far.)