"Kōji is a prominent character in the Japanese manga ""Jerk Transformation Plan"". As the younger brother of the protagonist, Shikuma, Kōji plays a significant role in the development of the story.

Kōji is first introduced as a young and carefree high school student who enjoys playing pranks on others. He is depicted as a happy-go-lucky individual who seems to have no care in the world. However, as the story progresses, it becomes apparent that Kōji is struggling with deep-seated emotional issues stemming from his troubled childhood.

Despite his shortcomings, Kōji is a loyal and devoted brother who deeply cares for Shikuma. He often puts himself in harm's way to protect his older brother, even when it means going against his own personal beliefs. Kōji's unwavering loyalty and steadfast courage make him a beloved character among readers.

Throughout the series, Kōji undergoes a significant transformation, both physically and emotionally. He grows into a mature and responsible young man who is willing to take responsibility for his actions. His newfound sense of self-awareness allows him to confront his inner demons head-on, and he ultimately becomes a better person for it.

Kōji's journey towards personal growth and redemption is a central theme in the manga, and his struggles and triumphs serve as a source of inspiration for many readers. His character arc is a testament to the power of transformation and the resilience of the human spirit.

In conclusion, Kōji is a complex and multi-faceted character who evolves significantly throughout the course of the manga. His unwavering loyalty, courage, and personal growth make him one of the most beloved characters in the series, and his story serves as a reminder that anyone can change for the better if they are willing to confront their inner demons and take responsibility for their actions."