An event that the people that were at challenge day go to that takes place later on the same day or soon after. Where they all get together and hug and kiss each other for several hours and sware there undying love to each other and everyone gets very emotional and which often leads to sex.
july 3rd is international xiao loving day. xiao day is a day where everyone gets to show their love for xiao from genshin impact, because he deserves it so so much.