|Voiced by||Asuka Tanii (Japanese)|
Ema Kogure (Japanese) (Episode 223-236)
Kristi Bingham (Funimation)
Judy Cheung (Hong Kong)
Leibi Wen (Taiwan)
|Age||13-14 (Estimation, around Natsumi's age.)|
|Species / Type||Pekoponian|
Yayoi acts like a typical high-school girl. Natsumi and Satsuki are her childhood friends, and out of the two Yayoi seems the most graceful.
She's also the president of the drama club, which seems to have a few other members as shown in the rehearsals of episode 29-A, although the other members have never been plot relevant, with the few times the club comes up being when Yayoi wants Natsumi's help for one reason or another.
- Satsuki Shiwasu-Childhood Best Friend. The two are always shown together, proving how deep their bond is.
- Natsumi Hinata- Childhood Best Friend. Natsumi barely spends time with Yayoi, due to being busy at home and helping the various sports clubs. The two see each other as friends nonetheless, Natsumi even gave Yayoi her strawberry when she gets turned into Natsuo.
- Kitajima - Member of the drama club who is unable make it to a play later in the anime due to eating one of Keroro's dangos.
- Giroro- Current Crush
- Keroro, Momoka and Saburo- Friends
Shimotsuki is the traditional Japanese name for the month of November.
Yayoi is the traditional Japanese name for the month of March.
- Her friend's name, Satsuki Shiwasu, is also formed from two traditional month names.
- Yayoi's special talent is spinning dishes. 
- Yayoi may be based off of Natsumi's Friends.