A character based on a cactus. He is the only "adult" in the studio puppet segments. While he is a friendly, older-brother figure, he can be a bit irresponsible at times. Being a plant himself, he is very knowledgeable about nature and loves green or thorny things. His friends include a prickly pear cactus and a rose. He refers to himself as "Sabo-san" and often ends his sentences with masculine particles like "daze" or "daro." When pressured by Kossy or Sui-chan, or when stuck for an answer, the bud on his head blooms. He then transforms into "Saboko," a slightly sadistic, effeminate persona whose catchphrase is "I'm gonna get all Sabo-Sabo on you~♡" and proceeds to playfully pounce on the two. However, Sabo-san treats Saboko as a separate person (or personality). For example, when appearing on "NHK Asobiva Manabiva," when asked by announcer Naoko Suzuki if Saboko was his friend, he replied, "Saboko is Sabo-san's biggest fan." When given water, he grows silky, medium-length hair. When something very sad happens, he freezes with his eyes and mouth shut, gradually growing more thorns until he becomes a real cactus. As a cactus, he is resistant to heat and drought but weak against the cold. He has friends who look very similar to him, such as "Dr. Sabonomizu." He lives with Kossy and Sui-chan. While they are friends, he is also depicted as their guardian, handling all the housework. He is a singer (and likely a singer-songwriter, as he is shown composing). In the show, he has a segment where he sings to his own violin accompaniment while introducing facts about nature. When overwhelmed with work, he often gets help from Ofuroski. Actor Sato, who provides the voice and operates the suit, has revealed that he incorporates improvisation. Saboko, in particular, occasionally drops old references that children wouldn't understand (like responding to the word "Nagi" with "Ah, Nagi no Balcony!" or approaching a character played by Masayoshi Yamazaki with lyrics from his famous song). As the only suit-actor character in the show, he has a high appearance rate in other programs, appearing as a regular in specials like "Kodomo Uta Matsuri" even without Kossy or Sui-chan.

A mysterious chair that can talk and move. He has blue legs and a light blue body. The blue part that looks like hair is actually a cover that can be removed or replaced. He has a distinctive verbal tic where he adds "-ssu" to the end of words (e.g., "Omoshiroi-ssu," "Tantei-ssu"). He always refers to rice as "Rice." He loves rice so much that when eating curry rice, he saves all the rice to eat by itself at the end. He is happiest when Sui-chan sits on him. While the puppet version has two eyebrows, the animated version in "Chair Town" only has a left eyebrow. He admires "Sugojiro," a popular manga character in Chair Town. His cousins include Swarin and a Kansai-dialect speaker named "Okossy." First person: I (soft, polite).

A consistently cheerful girl. First person: Sui or I. She is full of curiosity and loves "finding" things. She is Kossy's good friend and also his rival. In the pilot, she was 4 years old and met Kossy while exploring an attic. The actress playing Sui-chan changes periodically, and her outfit varies by era. The first wore beige overalls; the second, grey and yellow overalls; the third, a pink long-sleeved shirt with beige trousers and suspenders; and the fourth wears a shirt with a yellow collar, purple top, and pink/white striped bottom with a pink and white tie and grey trousers.

The main character of the "Yonda?" (Did you call?) studio segment. First person: I (soft, polite). A mysterious man who responds to the audience with "Did you call? You called, didn't you?" even though they didn't. There is a legendary episode where he actually realizes the audience didn't call him. He usually appears while in the bathtub and challenges child viewers with "Can you do this?" The challenges usually involve crafts or drawing and have nothing to do with baths, but one shouldn't overthink it. He also appears in the "Yondance" segment that started in 2017. While he mostly appears alone, he sometimes interacts with Kossy and Sabo-san in the Sunday edition. He also performs some of the ending songs.