For this one, Youmu-chan doesn't care one bit about actually introducing the holiday to you or what it means. For 4/20, she just wants you to buy the cute t-shirt she's so proud of.
*smug*April 20th is Strawberry Jam Day!How about that!? I made this original T-shirt myself!I could sell this!...in the world, you know!?There is no one sweeter than me...