That rabbit should be the official Scarlet Devil Mansion Library Pet, or something.
This whole page is so cute...
The ace of hearts!It's already the season for the year-end party, huh...Flick!*lift**pick*Magics and WizardsPartyBefore, I did stuff like drinking and spitting out a goldfish...Stuff like this......my skills are all rusty now....or this...The stars multiplied!It's a rabbit!!Mukyuu...Please choose......any card you like....or escaping from inside a giant glass tank, or all kinds of other stuff, but......or this......or this......is all that I can do anymore.Scarlet Devil Mansion*pull*