Both series take place in a post-apocalyptic Earth with child protagonists who don't understand how the world around them works. Despite that, they enjoy their lives and interact with the other lifeforms that exist in the same space as them.
Rojica is a bit more comfy than Ginga, but the series both ultimately have a similar atmosphere. Certain aspects of how humanity met its demise are very similar too.
They're also both short reads!
