|Voiced by||Takehito Koyasu (Japanese)|
|Species / Type||Pekoponian Andriod|
Ryusei (リュウセイ Ryūsei) is a character in the Keroro Gunso anime. Ryusei is introduced as part of the singing dancing idol invader unit, Operation Maru-Otsu (〇乙). However, he's actually an android remote controlled by Kururu.
Ryusei is Kururu and he makes little effort in hiding his personality. He soon is taking a bath right in the Hinata's yard, filled with curry packets. Natsumi's lack of reaction to that leads to him attempt to get her attention several times throughout the episode by doing bizarre things involving curry, and even laughing like Kururu usually does. However, she never reacted to any of it.
Kururu researched tastes of Pekoponian girls and created 5 androids that fit their preferences. Kururu controls Ryusei using the Invasion Substitute System through a special control room and full body suit hidden inside the Keroro Platon Headquarters.
In episode 320, the platoon invade using the android suits, only to be surprised when Natsumi Hinata easily bows down to them with little resistance. Ryusei takes a bath on the Hinata's backyard with several curry packages on the water, but Natsumi just worries about him getting dizzy due to the heat, completely ignoring the bizarreness of his behavior.
Eventually, the second phase of the plan is put into action. However, Ryusei ignores it all and starts a breath challenge where he puts his head into a plate filled with curry to hold his breath for as long as he could. However, Natsumi just ignores him.
Natsumi shows the headquarters of the Keroro Platoon to them, and tell them they can stay there since there's no one there. At this point, Ryusei carries a plate of curry on his head and does Kururu's signature laugh, but once again Natsumi just ignores his odd behavior. Reiji protests, saying that someone must live there. However, Natsumi calls Keroro and the others worthless garbage, before saying that she'd easily let the idols invade. In Natsumi's dream image of their invasion, Ryusei is seen carrying a plate of curry on his head, so she did notice his oddity, but doesn't seem to want to let it destroy his image of him.
Furious with her behavior, Akira and the others break character and accidentally drop a false wall, revealing their hidden command chambers where the Keroro Platoon actually were hidden. They accuse her of letting anyone invade if they're hot, but in response Natsumi just furiously beats them up.
- All the Operation 〇乙 members are based on Gundam Wing characters. Ryusei's appearance is based on Zechs Merquise, who shares his Japanese voice actor with Kururu.