User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-36663391-20180821131242/@comment-1359322-20180822023244

12 is the number of decades Ise will not get laid. XD

On a serious note, 12 may be the number of years before Ise first gets a child, if Kurenai is 18 in 30 years from now, 12 would end up being a time Ise gets his first son.