Gaijin Goomba is the Leader of the Gaijin Gamer gang and MatPat's right hand man. He's a video game analyst who focuses on culture, especially (but not exclusively) Japanese culture. His main show is Game Exchange.
He has his own adventure too where he goes to collect the 7 goomba asses in order to save the world (wait, why is the number of mandatory collectables in RPGs always 7 what the fuck let's make it 7.5 then)
Bench Squad 1.5
Gaijin Goomba prevents Toad and The Juicy Shroomass to take their new hideout. Toad made fun of Aki Goomba, even calling her a "Big titty dildo slut!" to piss Gaijin Goomba off as Toad punched him in the (non-existing) dick and killed him.
Goomba got Back: The Game
Gaijin is the main protagonist of this game so therefore he is the only character in the game (aside from Lonely) who is able to use PSY Gooms (you get to name it).