My uncle has a quote which not only has stuck with me my whole life ever since he first said it aloud but also perfectly captures the spirit of Karakai Jouzu no Takagi-san without any troubles.
“If we ain’t teasin’ ya, then we don’t like ya.”
It may seem counterintuitive, but it’s true. Most people are not comfortable being playful with complete strangers, and even more people avoid interacting with those whom they dislike. So, teasing is, in a way, another term for caring.
My family and I tease each other all the time whenever we have get-togethers, yet Nishikata and especially Takagi take the medal for teasing champions as their relationship plays out in kindhearted fashion.