Skinship

Skinship - "The act of intimate, non-sexual touching between very close (usually same-sex, but not always) platonic friends. It involves acts such as holding hands/arms, hugging, snuggling and kissing on the cheeks.

The concept originated in Japan, where social interactions and dealings were considered more intimate and relaxed when they took place within a communal public bath due to the belief that group nudity helps break down the barriers and helps establish a closer relationship.

It has also evolved to define a situation of intimacy derived from the touch of skin or close proximity thereof, although in Korea, as well as some other places, it has come to also mean sexual contact, heavy petting and related activities.", Urban Dictionary

"It's not unusual to see Koreans walking and holding hands with each other, even if they're not in a relationship. That just means that they have a deep skinship with each other."