Eiichi Suo is introduced as a former champion coach in the world of Neo Pro-Wrestling, having previously trained the legendary wrestler Aquamarine. By the time he takes on the role of coaching the Pretty Four, however, he has descended into a state of burnout and heavy drinking. He is often depicted as a disheveled figure, frequently seen wearing traditional geta sandals and carrying the weary demeanor of a man haunted by his past.

His personality is gruff, eccentric, and seemingly detached. Suo is a flagrant alcoholic, and his initial approach to training is brutally simplistic and harsh, relying on methods such as forcing the team to perform extreme numbers of push-ups and sit-ups. He is not a character who offers easy encouragement or warm camaraderie. Instead, he presents a tough, no-nonsense exterior that can come across as indifferent or even cruel. Despite his rough edges, he possesses a sharp perception and is often the only one willing to deliver blunt truths to his team, cutting through their egos and complaints about the intensity of their regimen.

Suo's primary motivation stems from a flicker of hope he sees in the newest member of the Pretty Four, Miku. Having lost his way after the height of his career with Aquamarine, he is portrayed as a man searching for redemption or a new purpose. He takes on the coaching position on the recommendation of Masayo, and rather than seeking personal glory, his actions are driven by a desire to see Miku’s inner fire grow. He aims to prepare the team not just for physical victory, but to help them understand the deeper, "shady secrets" behind Neo Wrestling.

Within the story, Eiichi Suo serves as the primary mentor and strategist for the Pretty Four. His role is to transform a group of popular but inexperienced wrestlers into serious contenders. He is responsible for the team's grueling physical and mental development, pushing them to their absolute limits. His training regimen, which includes unusual methods such as training in the ocean with scuba gear, is designed to unlock their potential. As the series progresses, he moves from being a seemingly washed-up drunkard to the anchor that holds the team together during their most difficult challenges.

The most significant relationship in Suo's life is with his former student, Aquamarine. She is the standard by which all other wrestlers are measured, and his history with her is a constant shadow over his present. His connection to Miku is also central; he sees echoes of Aquamarine's raw talent and determination in her, making Miku the focal point of his resurgence as a coach. With the other members of the Pretty Four, Ginko, Sayaka, and Nana, he maintains a professional distance, focusing entirely on their athletic performance rather than emotional support.

Over the course of the series, Eiichi Suo undergoes a subtle but notable development. He begins as a broken man simply going through the motions, but his commitment to the team reignites his passion for the sport. While he remains a hard-edged figure, his dedication becomes undeniable, and he is widely regarded by viewers as one of the most developed characters in the series, possessing a depth and backstory that adds gravity to the narrative. His journey is one of a mentor finding his own path to redemption through the success of his pupils.

Regarding notable abilities, Eiichi Suo does not possess fighting skills as a wrestler. Instead, his abilities are purely strategic and pedagogical. He is recognized as a coaching genius, capable of identifying a wrestler's hidden potential and designing extreme training regimens to draw it out. His true skill lies in mental fortitude; he prepares his team for the psychological warfare and high-pressure environment of championship wrestling. His methods, while unorthodox and severe, ultimately prove effective in elevating the Pretty Four to face the top rivals in their sport.