A chojin that is styled after a baby.
Peek-a-Boo is a chojin that starts his matches as a baby, as Strong the Budo forces him to revert to a baby form after every match that he wins. He learns with the speed of a baby and is able to assimilate all of his opponent's moves with ease, but struggles to remember basic moves once he reaches an adult form. He learns the power of friendship and changes his ways after being defeated by Kinnikuman.
During Chojin Fan Appreciation Day, Peek-a-Boo appears with a group of Perfect Chojin from the air.  He and his group announce that the Hell Missionaries were just advance troops, whereas they hold true power.  A tournament is then announced between the Perfect Chojin and Seigi Chojin.  After Max Radial's death, Peek-aBoo helps create a giant machine-gun and enters into a chamber.  He - along with his colleagues - are shot out and create giant holes in the concrete beside the ring. 
Peek-a-Boo vs. Kinnikuman
Peek-a-Boo appears in Ryogoku Sumo Hall.  As Kinnikuman is the representative of Japan, he is designated as the opponent of Peek-a-Boo.  Kinnikuman and Meat Alexandria go to the stadium to fight, where Kinnikuman takes pity on a crying Peek-a-Boo, but - after making Peek-a-Boo laugh with a game of peek-a-boo - Peek-a-Boo uses the hands on his stomach to reveal a monster and scare Kinnikuman.  He then proceeds to attack Kinnikuman with a series of kicks. 
Kinnikuman eventually manages a tackle and a Waterfall Drop.  When Terryman criticises Kinnikuman for taking so long in his match, he exchanges a rapid series of blows with Peek-a-Boo, but Peek-a-Boo appears weak and can only cry in response to the attacks.  After Kinnikuman cradles him to stop the tears, and plays piggy-back, Peek-a-Boo uncovers his face and reveals he has been learning from Kinnikuman. He starts to attack in earnest. 
After issuing a series of attacks on Kinnikuman, he moves away the hands from his abdomen to reveal his true face of fear, which has the appearance of a demon.  Meat reveals that Peek-a-Boo learns with a baby's speed, which means he is assimilating all of Kinnikuman's moves. When Kinnikuman tries to use a Kinniku Buster, Peek-a-Boo counters is with ease.  He goes on to use a Big Baby Bomb.  It is revealed that Strong the Budo 'resets' Peek-a-Boo after each match, and he argues with Strong the Budo about his refusal to revert back to his old form. Kinnikuman - during the conversation - is able to Body Slam Peek-a-Boo. 
Kinnikuman realises that Peek-a-Boo has not assimilated his most basic moves, as he did not use them during the match, and so he gains an advantage by using them.  Peek-a-Boo also has evolved so quickly, that he has forgot the basics by learning so many advanced moves. Kinnikuman uses a series of attacks, culminating in the Furinkazan.  Peek-a-Boo - once defeated - learns about the power of the heart and Yuujo Power.  Kinnikuman convinces him not to commit suicide in defeat, but to find Neptuneman and become stronger than he is at present. Peek-a-Boo tells Strong the Budo that he made a promise to Kinnikuman for a rematch, so he will not kill himself in shame. 
Before Kinnikuman vs. Nemesis
For most of the arc, Neptuneman is jailed by the Perfect Large Numbers for committing treason against Perfect Chojin. Peek-a-Boo frees Neptuneman just in time for Kinnikuman's match against Nemesis. Just as Kinnikuman is about run away from his destiny, Neptuneman gives Kinnikuman a pep talk with the help of Peek-a-Boo. Kinnikuman's kindness helped out another Perfect Chojin. Kinnikuman must fight Nemesis!
Both Neptuneman and Peek-a-Boo are confident that Kinnikuman can convince Nemesis to change the Perfect Chojin world for the better. It's time for a revolution for the Perfect Chojin world. The current rules are holding the Perfect Chojin back. Neptuneman admits that Silverman was right all along. Neptuneman tried to start a revolution, but it failed miserably. An outsider like Kinnikuman could be the change that the Perfect Chojin needed.
Despite this encouragement, Kinnikuman refuses. Neptuneman brings up his victories against Ramenman and Robin Mask. However, Kinnikuman thinks that those victories were pure flukes. Kinnikuman brings up how Nemesis defeated Ramenman and Robin Mask in fair fights. Kinnikuman is just a phony.
Irritated by Kinnikuman's self-loathing, Neptuneman places him into a chokehold. Neptuneman asks if Kinnikuman's victory against him is a fluke. Kinnikuman says that it was. After Neptuneman slaps Kinnikuman aside, Neptuneman decides to kill Kinnikuman with a Quarrel Bomber. Kinnikuman dodges the Quarrel Bomber with ease. However, Neptuneman does another one, but with his Diamond arm. In self-defense, Kinnikuman decides to charge at the Quarrel Bomber and activates his Fire of Inner Strength. As Neptuneman says, "[A person] can leave the ring, but the ring can never leave [them]."
And with that, Neptuneman and Peek-a-Boo leaves. Kinnikuman thanks Neptuneman for the pep talk as he returns to his restoration capsule. During the match against Nemesis, Neptuneman and Peek-a-Boo cheered on Nemesis.
Big Baby Bomb
- Uses the arms around his abdomen to create a perfect clutch and slam his opponent into the canvas
- Perfect Fright
Win/Loss Record (Singles)
- X Kinnikuman (Furinkazan)
- Submitted by: Seiji Tanaka (田中青志) of Miyagi
|Strong the Budo|
|Perfect Large Numbers|
|Max Radial, Turboman, Crushman, Dalmatiman, Marlinman , Peek-a-Boo|
|New Perfect Large Numbers|
|Marvellous, Jak Chi, Nemesis, Polarman|
|Mirageman, Abyssman, Painman, Psychoman, Ganman, Thingman, Crowman, Justiceman, Goldman, Silverman, The Man|
|Qilinman, Screw Kid, Kendaman, Neptuneman, Big the Budo, Omegaman Dexia, Mammothman, Seiuchin|