Cyber

After discovering the Keroro platoon they began covertly gathering information on each member and their attached human companion, the only one who suspected anything was Dororo - but their disguise abilities allowed them to pass as a regular human. Gathering information on their weaknesses, Cyber (after contemplating how both hilarious and messed up each member of the platoon was), intended to dispatch of them due to the threat they presented to Pekopon.

However, Cyber changed their mind once they realized the platoon was a much more... managable threat to the planet, and getting rid of them would simply make the planet a bigger target. They also found each member charming in their own way, and openly admitted that it would've been a little sad if they had to get rid of them.

After that Cyber began hanging around, mostly becuase they were bored and the platoon and their humans was the closest thing Cy has to friends. They developed an odd friendship/romantic tension with Kururu, with both parties seemingly attempting to annoy the other into falling in love with them. They also have a "cool uncle" bond with many of the kids, and should a threat present itself does not hold back the destruction they were made for.

From their intial research, Cy considered the Sergant Major the biggest potential threat, and that opinion didn't change even after becoming his "friend". But Cyber did eventually soften on him quite a bit after seeing his mask slip enough times. Their friendship seems based on bickering and playfully messing with one another, but both are actually deeply protective of the other. Not that they'd admit it of course.

Dororo is Cyber's second closest pal, with Cyber coddling him like he's the sweetest little thing. Dororo sometimes finds it embarassing, but does enjoy having a friend that actually looks out for him.

Out of all the humans, Saburo is the one Cyber is the most paternal towards. Despite recognising that the boy is very independant Cyber worries about him being in danger.