Volume 4 of Arakawa Under the Bridge collects manga volumes 7-8 in an omnibus edition and features story and art by Hikaru Nakamura.

And so the river bank denizens begin training that will let them go to Nino’s extraterrestrial hometown. But do any of them have what it takes to make it in space? A trip upstream brings Rec into contact with a tribe ruled by an Amazoness, who soon sees Nino as her rival. Everyone helps build a house for the Mayor and a park for the Metal Brothers. As the cast of characters expands daily life on the river bank becomes ever more eventful…