Oops, it doesn't look like 'own vi day' is a national day..

Other days

stud

Stud Day
nail polish

Nail Polish Day
cat girl

Cat Girl Day
cuddle up

Cuddle Up Day
frozen yogurt

Frozen Yogurt Day
youth

Youth Day
get funky

Get Funky Day
ask out your crush

Ask Out Your Crush Day
believe

Believe Day
slime

Slime Day