"Walpurgis Night (Walpurgisnacht) is a traditional spring festival on 30 April or 1 May in large parts of Central and Northern Europe. It is often celebrated with dancing and with bonfires. It is exactly six months from All Hallows' Eve."
Be sure to celebrate this festive day by making a contract with Kyubey and becoming a magical girl. en.wikipedia.org/wiki/Walpurgis_Night