Yeah, that's a football. Between that and the kettle (used for holding drinking water), we're meant to see Keine as a coach's assistant or some such. It's a staple that I've seen a few times before, though the only example I can remember offhand was in Full Metal Panic? Fumoffu.
Arise, Mokou...!Heh...that's a pretty fiery punch you got...You...are the final hope for a world on the verge of being enveloped in darkness!TOTTERBhff!Mokou, you coward!KlopReached all the way to my heart...heh heh heh heh heh...!Stupid Mokooooou!As a bearer of the sacred light, you will gather the Silver Gear and stop the Fact!SHOVE