Prior to the knockout stage of the World Youth, he was always Wakabayashi's main rival for the regular goalkeeper position. He has being Hyuga's best friend and both of them have played football together since childhood. Partly because of this, he has no intention of taking over his father's karate dojo and training school.
Kids' Dream arc
After being considered by both Kojiro and Kozo Kira themselves, Wakashimazu became Meiwa FC's keeper; however, a car accident, where he save a dog from being hit by a small truck made him unable to play until Meiwa's match against Furano Elementary Soccer Club. He suffered broken left shoulder and left leg, and He used to be a karate practitioner before becoming a keeper; known for this as the “Karate Keeper”, Ken uses his karate skills and speed to his advantage as a keeper.
Boys' Fight arc
Wakashimazu followed Hyuga to the Toho Academy, becoming a regular under the teachings of Makoto Kitazume. Wakashimazu's father wanted him to focus more on karate and be part of his own dojo, the Wakado Style, as he never managed to win the football national tournament against Nankatsu's two victories in a row. He and his father discussed this situation and reached an agreement: if Toho did manage to win this time, he would allow Ken to keep playing football, but if, not, he'd return to the dojo and become the heir. As a result, Wakashimazu was determined to win the national tournament to earn his freedom and keep on playing football; he also became Toho's captain during Hyuga's absence, keeping the team together aided by Sawada, and for the time he was put on the bench.
Wakashimazu managed to keep on playing football thanks to a shared victory with Nankatsu (in which he almost managed to catch Tsubasa's Drive Shot); after the tournament, he was chosen as the regular goal keeper of the Japan Jr. team.
As Wakabayashi joined the team, he trained fiercely, thinking to be in competition with him for the GK position; but having injured against Hamburger SV Jr. Youth, his injury awakened and even worsened during the match against France. While he was vital in the Japanese victory, having blocked Louis Napoleon's shot during penalties, he wasn't able to play the final match.
Battle of World Youth arc
Winning the tournament three times in a row with Toho Academy high school and his captain Hyuga, after the test matches against Holland Youth, Wakashimazu, like most of the other Japanese, wanted to focus on the Japanese Youth team. However, after a quarrel with coach Mikami about the regular goal keeper position (refusing to yield his position to Wakabayashi simply based on his playing professionally in the Bundesliga), he changed his mind and left the team, joining the J-league, in the Yokohama Flugels team. Progressing individually in the J-league, he still showed worries over Japan Youth, and even wanted to play during a pinch, before seeing Wakabayashi on the field.
Helping Hyuga with his mother's hospital expenses thanks to the money he earned in the J1 League, he was convinced to go back to the team. He also decided to adopt a more aggressive style of playing (style similar to the one adopted by Mexico's GK Espadas). Having proven himself time and again, he accepted to be Japan's second keeper without problems, acknowledging Wakabayashi's skills.
At some point, Wakashimazu became a 5th Dan in Karate and started having his own disciples as well, such as Shun Nitta. In Golden-23, Coach Kira decided to employ Wakashimazu as a forward (and it's also revealed that he had first wished to play in attack, but when Hyuga took over, he went to be a goalkeeper for the sake of the team), and he performed very well. He scored a goal in the friendly match against Nigeria and performed numerous post play.
Rising Sun arc
Wakashimazu continued to be a forward, as a two-top with Kojiro Hyuga. On the match against Germany, since he was benched on 2nd half-time and Wakabayashi was heavily injured by Schneider on his back, Morisaki was the substitute keeper against the Germans.
To be updated as series follows.
He is a fairly reserved person and very strict with his training and a man of few words. Nonetheless, he's fierceful while on field, quite faithful to his best friends Hyuga and Sawada, and cold but polite in normal situations.
Ken's biggest faults are his pride and slightly conceited attitude, especially regarding his worth as a player. While not wrong about Mikami's bias towards Genzo, he reacted near violently towards Mikami when confronting him about it, and later decided to withdraw from the team despite them desperately needing him due to Genzo's injury. He does begin growing out of it after his return, however.
- Main article: Ken Wakashimazu/Techniques
- Main article: Ken Wakashimazu/Gallery
- His name is Richard Tex Tex in the Latin American dub and Ed Warner in most European countries. He is named Ra'd (رعد) in the Arabic dub. The Latin-American name is based on puns coming from his and Roberto's Latin-American VA, Ricardo Tejedo.
- In the 2018 anime, because Hyuga does not like wearing the captain's armband, Wakashimazu wears it for Toho Academy instead of Sawada due to his older age. He also took over the role outright when Hyuga was suspended for the middle school tournament.
- Mentioned on World Youth Hen chapter 52: "The Entrusted Ball", after using the Wakado Style True Fist Defense against Mexico Youth.
- A feat he wasn't able to accomplish at the time, and only later the Italian Gino Hernandez was the first keeper to be able to do this against Tsubasa.