- Name: Yosaku (与作)
- Classification: Human
- Homeland: Japan
- First Appearance: Manga Chapter 5, Anime Episode 1
- Seiyu: Tetsuo Mizutori
Yoshino Yosaku is an odd little guy who often pops up wherever there's a TV camera, doing an impromptu naked fan dance. In the anime he is known for appearing just about anywhere and performing numerous jobs, most notably working at Kinnikuman's favorite gyudon place. He also will often fill in as announcer with Kazuo Nakano.
He appears frequently throughout the series as several different character, including a Roots Island native, and had a longer tenure than the more recognizable Nakano-san. An elderly Yosaku makes a cameo appearance in Kinnikuman Nisei volume 25, chapter 248. Some of his most notable appearances were an eyewitness who claimed to see Nessie, Kinnikuman's Rocky-obsessed boxing coach in the tradition of Mickey Goldmill and the janitor at Himeji Castle who finds Bikeman.
His nickname is Be Anywhere Do Anything Yosaku-san (何処にでも出てきて何にでもなる与作さん, Doko ni demo Detekite Nani ni demo naru Yosaku-san).
- Volume 1
- Himself/Nessie eye witness (Chapter 5)
- Road worker (Chapter 8)
- Volume 2
- Himself (Chapter 18)
- Himself/Scared citizen (Chapter 22)
- Himself/Boxing coach (Chapter 24)
- Elder Yosaku (Chapters 26~27)
- Oh! I don't understand what he's talking about, but what superb confidence! (お～！言葉の意味はよく解らんが、とにかくすごい自信だ！ O~! Kotoba no Imi wa yoku Wakaran ga, tonikaku Sugoi Jishin da!) - usually said in response to Kinnikuman's nonsensical proclamations.
- I-I... don't want to see what I'm seeing!! (オ、オラ…見てはならねぇものを見てしまっただ～!! O, Ora... Mite wa narane mono wo Mite shimatta da~!!) - usually said when he sees something scary.