 If you liked
Keroro Gunsou
|
 ...then you might like
Shichinin no Nana
|
Sgt. Frog's artist, Mine Yoshizaki, created the character designs for Seven of Seven.
there is various crossovers exist between Sgt. Frog and Nana 7 of 7.
Also, in episode 89 of Sgt. Frog, it features a plot that splits Corporal Giroro into seven personalities, most of whom resemble Nana's split personalities