[2025 Latest] Did Koji Mizukami fail to play in the Koshien tournament? What was the story behind his days immersed in baseball at a powerhouse school and his decision to pursue acting?

Actor Mizukami Koji was the vice-captain of a strong school that missed out on the Koshien tournament during his high school days. This book thoroughly covers his grueling training, tough relationships, his encounter with theater, which led him into a new world, and his path to blossoming as an actor, along with the emotional upheaval of his student life.

table of contents

1. His high school days and results as he aimed for Koshien

2. Rigorous training and interpersonal relationships at Soseikan High School

3. Why I realized I couldn't continue playing baseball

4. The change in my mind after joining the drama club

5. The process leading up to debut in the entertainment industry

6. Background of university entrance and dropout

7. How does your baseball experience inform your acting?

8. Q&A: Frequently Asked Questions

1. His high school days and results as he aimed for Koshien

Mizukami Koji is originally from Fukuoka Prefecture, but went on to attend Soseikan High School in Nagasaki, a prestigious school that has played in the Koshien tournament. He has devoted most of his life to baseball, which he has been playing since he was in the second grade of elementary school, and continued to practice hard in high school with the goal of playing in the Koshien tournament. However, his team was eliminated in the best eight of the Nagasaki Prefectural Tournament, and was unable to make it to the Koshien stage.

He said he had no regrets about the result. He was able to accept it calmly rather than in tears because he was confident that he had done everything he needed to do.

2. Rigorous training and interpersonal relationships at Soseikan High School

The baseball team at Soseikan High School had a tough environment with almost no days off throughout the year, with practice continuing from morning until night. Practice was not interrupted even on rainy or snowy days, and Mizukami led such a stoic lifestyle that he would start practicing on his own early in the morning to coincide with the 8:00 a.m. practice start. Living in a dormitory meant that the space available to him was very limited, making it difficult to live in a group while maintaining discipline.

His role as vice-captain also brought a lot of pressure. He was constantly responsible for reminding others to keep the shared spaces clean and for enforcing discipline. Mizukami recalls that because the seniority-based culture was still very much in place, he was sometimes subjected to unreasonable remarks. Even in such circumstances, Mizukami felt it was important to maintain "proper hierarchical relationships that respect seniors," and he and his fellow vice-captains divided up roles and brought the team together.

■ Basic information from Soseikan High School

item	Content
school	Soseikan High School (Isahaya City, Nagasaki Prefecture)
position	catcher
role	Vice Captain
life	Dormitory life and nearly year-round practice
the goal	Koshien Tournament Participation
result	Nagasaki Prefectural Tournament Best 8

Although he found human relationships and group life difficult in such a harsh environment, he continued to support those around him with his straightforward personality.

3. Why I realized I couldn't continue playing baseball

Mizukami says that he realized he had reached the ceiling of his abilities when he was in his first year of high school. He had been blessed with a good physique and had achieved some success up until junior high school, but when he entered high school, he was confronted with surprisingly skilled athletes from all over the country, and he realized the clear gap between them.

Having decided that it would be difficult to become a professional baseball player, Mizukami shifted his focus from technical skills to becoming a vice captain, where he could contribute in both lifestyle and mental aspects. He placed importance on basic lifestyle habits, such as greetings, courtesy, taking good care of equipment, time management, and caring for teammates, and became a key supporter of the team.

At the same time, however, he looks back on his high school days and calmly analyzes that he was "too serious" and that he may have imposed his values too heavily on others.

4. The change in my mind after joining the drama club

After retiring from the baseball club, he accepted an offer from the drama club advisor and tried his hand at acting for the first time. For someone who had only ever known baseball, the opportunity to experience a new world was a great stimulus, and his curiosity and desire to "give back to the school" motivated him to take up the challenge.

He says that the friends he met in the drama club had completely different values and ways of looking at the world, which surprised him a lot. There are some similarities between baseball and drama, such as having to play a role in a group, and his previous experiences proved useful in unexpected ways.

After trying his hand at acting, there was such a change in his demeanor that rumors spread among his juniors on the baseball team that "Mizukami-senpai seems to have become kinder." It also gave him an opportunity to objectively look at himself, who had been playing the "strict role" of vice-captain.

5. The process leading up to debut in the entertainment industry

After graduating from high school, he planned to go on to Fukuoka Institute of Technology and continue playing baseball. However, his experience in the drama club made him interested in working in the entertainment industry, and he joined an entertainment agency that had been offering him offers for many years. He then auditioned for the TV drama "Chugakusei Nikki" and was accepted with flying colors. If he had been rejected, he had intended to continue playing baseball at university, but he ended up pursuing a career in the entertainment industry.

He said that on his first filming location, everything was new to him, and every day was filled with excitement. Looking back, he said that he just tried desperately to adapt without any standards of judgment, and his words give us a glimpse into the origins of his acting.

6. Background of university entrance and dropout

Although she continued her entertainment career while remaining enrolled in university, as her workload increased she found herself unable to find time to attend classes, and as a result was only able to attend for the first month or so. After about two years, her father suggested that she might find it difficult to continue attending university, and she decided to drop out.

His parents had made it possible for him to return to university at any time, so the financial and administrative costs involved were certainly not a small burden. This is also an episode that shows the magnitude of his family's support.

7. How does your baseball experience inform your acting?

Mizukami says that his experience in baseball has had a major impact on his expressiveness as an actor. He says that the idea that just as no two games are the same, no two plays are the same naturally comes in handy when playing different characters in each production.

The patience and mental strength he developed during his baseball days are a valuable asset in the long hours of filming and working with different actors and staff every day. His stoicism in pushing himself remains unchanged to this day, and he says that on days when he can't live up to his ideals, he "feels depressed every day." His attitude of continuing to work hard is what supports his current brilliance.

8. Q&A: Frequently Asked Questions

Q1. Did Mizukami Koji play in Koshien?
They did not participate. They were eliminated in the best 8 of the prefectural tournament.

Q2. Were you famous in high school?
He became a hot topic on social media as a "super handsome baseball player."

Q3. Is it true that you were vice-captain?
That's true. My role was to bring the team together in daily life.

Q4. Why did you decide to try acting?
The reasons were that I had a complex about only knowing baseball, I wanted to see a new world, and I wanted to give back to my school.

Q5. Why did you become an actor?
Fascinated by the joy of acting, I decided to pursue a career in acting after passing an audition.

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