Sirotan has many friends. Some of the Sirotan merchandise features his friends as well as him.

	Kametan (Widdle Turtle) He is Sirotan's best friend. He likes corny jokes. He hearts Usamomo.
	Usamomo and Marumaru (Peach Bunny and Roly-poly) Usamono like grows and arranges flowers on a pretty hill and goes monthly into town to sell them. Marumaru is Usamomo's pet.
	Penta (Widdle Penguin) He loves to talk. His favorite food is ice cream. He is bitter towards movement...
	Mokota (Widdle Fluffy) Since he wears a wool coat throughout the year, in the summer he is sweaty and itchy. Unfortunately, his skin has been sunburned badly.
	Panya no Shirokuma-san (White Bear-san the Breadshop Owner) Once upon a time, he wanted to make the tastiest bread in the world. He also loves to read books.
	Iruka-kun (Dolphin-kun) He is good at jumping. He is very popular since he is so active. なぜか大阪弁をしゃべる。
	Mirumi (Like Seeing Milk) She is the only daughter of the milkman who has delicious milk. She recommends their original "Megumi Forest Milk."
	Keekiya no Seiuchi-san (Walrus-san the Cakeshop Owner) She is an older sister. Even though she is young, her skills are first class. Everyday, she makes a new work.
	Kani no Chokkii (Crab Coat) His sissor-like claws cut well. He lives on the sandy beach. He likes to race, but Sirotan always wins.
	Osakana San Kyoudai (Three Fish Brothers) The siblings all together are mailmen. The eldest son is efficient, the second son is active and lively, and the third son is carefree.
	Ramama to Ratsutsu (Otter Mother and Otter Baby) They are parent and child. The mother is the charismatic Sea Shell Jewely Shop owner who attracts many customers. The baby loves mischief.
	Jyugon Ojisan (Dugong Uncle) すぐかんちがいする。自分を人魚だと思いこんでいる。 Surprisingly, he has a small appetite. He says, "dawasa." 口ぐせは「ダワサ」
	Kujira-san (Whale-san) The size of his body is not beaten by anyone. His favorite food is bread. He does not give the appearance of a small thing and he has a huge heart. 小さなことは気にしない心も大きなクジラさん。
	Pipipi Shimai to Mama (Chick Sisters and Mama) The mother gave birth to three chicks accidently in the water country, but Sirotan luckily rescued them.
	Shachi-kun (Orca-kun) 頭はよいけど、おこりっぽい。 人気者のイルカくんに、しっとしているみたい。 しろたんをさわるのが好き。
	Manbou (Ocean Sunfish) いつもボーっとしている。 あまり動かないので、置き物とまちがわれたり・・・。
	Kame Sensei (Teacher Turtle) He is a calligrapher. He was Sirotan's father'teacher. 人里はなれたところにすむちょっとかわった先生。