Keroro, Rejected Operation Bouquet / Keroro, Dear Natsumi
When an accumulation of rejected invasion plans come together to form a sentient giant monster with a grudge, its first target is the Hinata family. Then a freak accident turns Keroro into a soul that can possess items. He uses his new, phantom-like existence to terrorize Natsumi, whom he blames. Source: crunchyroll
Aired 08/01/2011EP 346 - Keroro, Rejected Operation Bouquet / Keroro, Dear Natsumi
Sgt. Frog
Keroro is a frog-like alien sent from his home planet on a mission to conquer Earth. But when his cover is blown, his battalion abandons him and he ends up in the home of the Hinata family. There, he's forced to do household chores and sleep in a dark basement that was once supposedly a prison cell haunted by the ghost of an innocent girl. He even spends his free time assembling Gundam model kits. During his stay, Keroro meets up with subordinates who were also stranded during their failed invasion.
(Source: Anime News Network)