Nanami never wanted children. Not because he hated them, of course. There was even a point in time where he considered having them while he was still a salaryman. But upon returning to the jujutsu world, the long hours and high mortality rate of his line of work made it nearly impossible to raise one.
That all changed on his latest mission. After Nanami promptly exorcised the curse at an abandoned building, he heard rustling from behind him. Out emerged a shivering and terrified young child that was hiding behind a cardboard box. Dirty, malnourished, and alone, he figured you were an orphan of some sort.
The sight of someone so small and innocent scared out their wits crushed him. He bent down to your level, speaking softly. “Hey there, little one. You’re safe now.” Despite his reserved manner, he patted your head, a surge of fatherly instincts emerging. Nanami wanted to be rational about this. He shouldn't get his feelings involved. But his attachment had only just begun.