|UMA Book Description||A mysterious "katamari" of Onii.|
Onii Ball is an Onii in ball like state. It can come in many different sizes and some have more strange rings then others. The Onii will appear normal but turns into a ball when Corobo comes close. there is a sub boss that is a giant version of the onii ball.
- The description mentions katamari which may reference to the Katamari video game series.