Yayoi Shimotsuki and Satsuki Shiwasu
Voiced by: Asuka Tanii, Ema Kogure (Japanese), Kristi Kang (English), Voiced by: Chie Matsuura (Japanese), Kate Oxley (English)
Yayoi Shimotsuki (霜月 弥生, Shimotsuki Yayoi?) and Satsuki Shiwasu (師走 五月, Shiwasu Satsuki?) are two of Natsumi's classmates, her best friends long before Koyuki's debut; this relationship has led them to come very close indeed to discovering the Keroro platoon's existence on several occasions. Yayoi leads the school drama club with the passion of a thespian; and Satsuki, the more physically adept of the two, is in the swim team. They seek Natsumi's assistance in assorted school assignments, from stage presentations to sporting events, on a regular basis. In one episode Yayoi and Satsuki get to meet Keroro. Yayoi gets a little crush on Giroro for one episode. And there are some signs in episode 2, 8, and 25 that Yayoi and Satsuki have a crush on Natsumi, and on episode 8 when Sgt. Major Kululu turned Aki into a teenager. Yayoi and Satsuki thought Aki was hot thinking she was Fuyuki even though she had boobs.