Nana heralds from a family of serial killers. She neglects to mention this to her husband, but when Iemitsu makes it clear he doesn’t expect Tsuna to join his family, Nana brings him into hers. This becomes a problem when Iemitsu changes his mind...

The last thing anyone expected was for the older twin to manifest Cloud Flames. (Or the one in which Tsuna is Xanxus' Cloud Guardian, flat-out terrifies anyone who's heard about him, has a younger brother who loves him, is possibly in a queerplatonic long-distance relationship with Hibari but will never admit it, and is the big brother you never knew you wanted in your life.)

This is a dark Alternate History arc that follows what might happen if Mukuro had decided to make Xanxus his tool of conquest instead of Tsuna.