Keroro's Underground Base is found underneath the Hinata Family's house. Visitors must climb a ladder found underneath the staircase and walk through the door with a 'star' symbol on it. Inside is Keroro's Room, first seen in Episode 1. There is a picture of military patterns on the wall, a Plasma TV, a stereo and a computer that Keroro uses to surf the net (In one episode, Giroro caught him chatting with housewives on a forum.) The computer is frequently used by Kururu as well. Keroro displays some of his Gundam Models on a shelf. He takes naps on a lounge chair in the room. To gain access to an even further underground base, you have to open a mini fridge and get sucked inside. According to Kururu nobody knows the full plans of the underground base because it is always in construction.
Facilities
Commander Room: The Room where the Keroro Platoon is mostly seen in, this is where you can check all the security footage and more.
Meeting Room: The Keroro Platoon tends to hold their invasion meetings in this room.
Gundam Model Display room: Keroro displays his most precious Gundam Models here. It also has two floors. Its first appearance was in Episode 8.
Hot Spring: The platoon often relaxes in this area.
Pururu's Clinic: When Pururu is staying with them, she stays in this room to look after her patient's health.
Kururu's Inventions Storage room: Kururu stores his inventions here.
Kururu's lab: Kururu spends 99% of his time in there inventing or very rarely, watching The Hinata family take baths.
Jurassic Paradise: The Room that Keroro's dinosaur park was about to happen in.
Radio Broadcasting Room: A room where the Keroro Platoon can host and produce Radio Shows. It was first seen Episode 19.
Sweet Potato Dangos Manufacturing Factory: The room where Sweet Potato Dango was made for Valentine's day.
Empty Field: A room that mimics the outside world.