It's the first day of spring, and Cirno and her friends are once again up to no good! But after stealing a strange box from Marisa's house, they soon find themselves over their heads as they discover some things are meant to remain locked up.

After a big battle against Eggman, Sonic and his friends get sucked into Mario's universe. At first, their main priority is to get back home, but they realize they must work together to stop an evil force, bigger than Eggman and Bowser's powers combined!

What happens when a bored resident of the human village decides to write insane, crackfics about the residents of Gensokyo? Crackfic Collection.