Rainbow: Nisha Rokubou no Shichinin is a manga written by and illustrated by Masasumi Kakizaki that was serialized in Shogakukan 's seinen manga magazine Weekly Young Sunday from November 2002 to July 2008, later moving to Weekly Big Comic Spirits until January 2010. Its 22 tankōbon volumes have sold over 3.3 million copies worldwide, and the series won the 51st Shogakukan Manga Award in the general category in 2006.

The cell has seven beds, but only six boys. The seventh bed remains empty, its sheets neatly folded. The boys wonder who their final cellmate might be. They don't have to wait long.

The first chapter of Rainbow: Nisha Rokubou no Shichinin , titled "Seven Boys, One Cell," serves as a harrowing introduction to post-war Japan's brutal reformatory system. It is widely praised for its stark realism and emotional weight, though it is notoriously difficult to read due to its graphic depictions of abuse. Chapter 1 Summary

| Character (Name/Nickname) | Brief Background | | :--- | :--- | | | An ex-boxer and senior inmate of Cell 2-6. He becomes the group's big brother and mentor, teaching them resilience, courage, and the value of friendship. | | Mario Minakami | A hot-headed but fiercely loyal boy, convicted of attempted murder. He is quick to fight for what he believes is right. | | Joe Yabuki | A fiery and rebellious individual with a background of struggling with poverty and violence. He is the first to extend a gesture of friendship to Sakuragi. | | Noboru Maeda ("Suppon") | A timid and intellectual boy. He is often bullied but seeks to use his wits to survive. | | Tadayoshi Sakuragi ("Baremoto") | A former judo champion who has experienced a fall from grace. He is physically strong and a loyal member of the group. | | Jōji Sasaki ("Heitai") | A quiet and resourceful individual who is often the one to find creative solutions to the group's problems. | | Kyōichi Hatanaka ("Kyabetsu") | A street-smart and loyal friend. He is known for his practical thinking and ability to handle himself in dangerous situations. |

Correction for clarity: The main young protagonist is . The villain is Ishihara Mario (the doctor). The third Mario is a minor character.

The key moment of occurs late at night. The six younger boys are shivering from cold and fear. Sakuragi looks at each of them, then at the ceiling. He traces an imaginary arc with his finger and says:

There is a panel where Rock stares at the ceiling of the cell after a brutal beating. The ceiling is cracked, stained, and feels like it is closing in on him. That single panel captures the entire theme of the chapter: hopelessness . Yet, in the middle of that darkness, there is a tiny ray of light coming from a high window. It’s a classic visual metaphor, but Kakizaki earns it.

As Kaito hesitated, unsure of how much to reveal, Yamato intervened, his eyes narrowing.

Chapter 1 - "The Ordinary Days"

Many manga pull punches. Rainbow does not. Within ten pages, you witness a boy being dragged to the "isolation room" from which few return unchanged. The art by Kakizaki is stark, hyper-detailed, and borderline uncomfortable. That is intentional.

We are introduced to six boys, but Chapter 1 focuses primarily on Rock (Rokurouta) and Mario. Rock is our eyes. He is tough, scrappy, and has the quiet fury of a caged animal. Mario is younger, more emotional, and represents the vulnerability that this place wants to stomp out.