1x11 - Ms. Vampire Who Lives in My Neighborhood.

Sophie is worried by Akari's strange behavior. Erie quips that Akari being strange is nothing out of the ordinary, but Akari's actually caught a cold. Being clueless about human sicknesses, Sophie panics. Erie claims to have medical knowledge and tells Sophie to leave it to her, but as that seems too risky, Hinata is called. When Hinata hears that Akari has a cold, she immediately rushes over in a flash.