Guts preforms a mighty feat of willpower and resists ruffling Niki's hair. He hates you Guts, calm down.

"Families are sh- dumb in general." He grumbles, sticking his hands in his pocket. "Never really planned to get involved in this sorta thing in my life but- ah dammit. Don't look so depressed jeez." He gestures to Niki's entire everything. "I'm taking you to the aquarium. Don't kids like aquariums?"

When Guts was a kid he liked swords. Maybe Niki would like them to. Would it be illegal? Yes. Would it be worth it? Absolutely.