Oops, it doesn't look like 'suna rintarou day' is a national day..

Other days

polyamory

Polyamory Day
my little pony

My Little Pony Day
eat what you want

Eat What You Want Day
lisp

Lisp Day
pumpkin

Pumpkin Day
china

China Day
lash

Lash Day
tulip

Tulip Day
comfy

Comfy Day
law

Law Day