Blocks is a Justice Chojin of Dutch origin composed entirely of interlocking plastic bricks, resembling toy construction blocks. His body can reconfigure into various forms after being shattered but contains a critical vulnerability: a distinctive black brick serving as his weak point. This structural flaw ultimately determines his fate in combat.

During the Chojin Olympics tournament, Blocks faces Kevin Mask. He demonstrates his strength by crushing a truck in a bear hug prior to the bout. In the ring, Blocks employs shape-shifting and modular reconstruction as his primary combat techniques. His documented techniques include:
- **Bookend Crush**: Transforming into a massive book to trap and crush opponents between its pages.
- **Sliding Cocobutt**: Configuring into a slide structure to launch his head at an opponent's abdomen.
- **Decoration Block**: Disassembling to envelop and assimilate an opponent's form.
- **Sensational Clone**: Perfectly replicating an opponent's appearance, abilities, and fighting techniques after using Decoration Block.

Against Kevin Mask, Blocks utilizes his replication ability to copy Kevin's form and techniques, gaining temporary advantage through superior raw power. However, Kevin identifies the black brick weakness during close combat. After forcibly dismantling Blocks' form repeatedly, Kevin exploits this vulnerability by destroying the core "brain" block with his Big Ben Edge finishing maneuver. This prevents regeneration and causes Blocks' permanent disintegration at the 10-minute, 36-second match mark. His remains are presented to onlookers as an act of mockery, confirming his death.

Blocks does not appear in subsequent story arcs or media beyond this tournament appearance.