COWA!(1997)

A contagious Monster Flu is spreading around town like wildfire. Can the town's troublemaker and his friends get the medicine in time to save everyone?!
Paifu, a half-vampire half-werekoala, is always getting into trouble. With his trusty sidekick, Jose the ghost, he's out stealing watermelons, befriending murderers and causing a ruckus. But not everything is fun and games when the contagious Monster Flu sweeps through town. If the sick monsters don't get some medicine within a month, everyone will die! But only the one who has the medicine is the Witch who lives high atop Horned-Owl Mountain...750 miles away! With the help of a former sumo wrestler, Paifu, Jose and tagalong Arpon are off on an adventure! But, will they get the medicine in time or will they become victims themselves?!

(Source: VIZ Media)