In a desolate landscape beyond a poverty-stricken city, a nameless protagonist known only as Junk Dog races through the dust on his motorcycle, his existence defined by his ring name and a talent for fixing MEGALOBOX matches with his friend Nanbu Gansaku. Despite his prowess, Junk Dog finds himself in a monotonous and unfulfilling cycle, neither content nor driven enough to alter his course. His life is one of discontentment and resignation, hidden in the shadows cast by fame's bright lights. Contrastingly, under the sun's glare stands Shirato Yukiko, heiress to the wealthy Shirato family. Seeking to elevate her status, Yukiko orchestrates MEGALONIA, a prestigious tournament to crown the MEGALOBOX champion, with plans to use the event to boost the family's brand. The current champion, Yuri, embodies discipline and talent, a paragon of excellence in the ring. As Yukiko manipulates the competition for her gain, a rivalry brews between Junk Dog and the formidable Yuri, setting the stage for a high-speed narrative where light and darkness collide in a thrilling showdown.