In this adaptation to faithfully capture the original Game Boy hit, Koyama plays the main villain, Giovanni, or Sakaki in the original Japanese version. Meaning he’s the true leader to Team Rocket. As Giovanni, Koyama perfectly captures the charisma on what an organized crime boss should sound like (at least in a Japanese definition), and knows how to keep himself in the dark to avoid authorities until the time is right. He is very collected, calm, manipulative, and an excellent contradiction to Red’s ideals, just like how a true villain should be.

Though the iconic X-Men breakout character has magnificently been portrayed by Cal Dodd and Steve Blum in Western animated adaptations and games, if anyone could interpret the character for an anime version, Koyama is certainly the man for the job. Thanks to his deep and rough voice, he can capture the soft and rough extremes Wolverine is known for depending on who he’s surrounded by. When he’s with his lovely Mariko, he can be romantic, but put him in a fight, he finds ways to express his berserker’s rage in a context appropriate to both the character and the anime genre. Koyama shows that Wolverine is a man that has lived life, and does what he can to get the job done, even if he has to break the rules. He ultimately captures his snarky humor and how he’s a bad ass in his own way for you to see.

Although Koyama does have villains on his resume, another (questionable) one happens to be Kuze, a cyborg whose prosthetic face doesn’t allow him to move his mouth as he talks. However, his voice does a great job of reflecting his facial expressions and his postures to reflect his intentions, confidence, and charisma. Many fans can’t argue that Kuze is a villain because he does have legitimate motivations to his actions, and Koyama’s performance has us convinced he’s fighting for a noble cause. In addition, Koyama’s voice also captures the character’s harsh experiences both as a a child and as an adult, and you can feel that he’s a man on a mission that he truly believes in.

From the world of games, there’s Saejima from Yakuza 4. If anything, this role is probably Koyama’s international break out since the Yakuza games have largely been released with their Japanese audio track. What makes this role distinguishing is that it allows him to use his native Kansai accent since real life yakuza tend to speak with such mannerisms, and when he interacts with Majima, his best friend, he likes to make fun of his attempts at speaking in it. What not only solidifies Koyama’s performance as Saejima, but as a seiyuu, is when he gives a speech of what it’s like to take a life when the audience cheers for him to kill his opponent as he fights in an illegal MMA fight. He delivers his speech with emotion and conviction, and it shows why he’s such an excellent actor. At first he’s angry, but when he talks about what it’s like to take a life, he gets emotional, reflects upon his sins, and when you watch this performance, you can’t help but want to forgive Saejima thanks to Koyama’s performance.

Without a doubt, Koyama’s true breakout as a seiyuu would have to be Mamoru Takamura in Hajime no Ippo. As Takamura he largely captures his worst qualities of having a highly inflated ego and libido, but you can’t help but love the character thanks to his amazing strength. What makes Takamura a great character is that he can talk crap and back it up. Thanks to Koyama’s performance, you get all of those dimensions to Takamura who can be wise when it comes to fighting, and someone who is just ridiculously idiotic outside of that world. Takamura has a larger than life personality, and Koyama finds that way to portray that, and still be afraid of Kamogawa’s (his trainer who is in his seventies), authority.