Mr. Y is one of the main antagonists from Streets of Rage 4.
Mr. Y is the son of Mr. X and the twin brother of Ms. Y. Along with his sister the two took over the Syndicate Crime Organization after their father's death, seeking to rebuild their father's criminal empire. After doing secret experiments the two created a device to mind control people and began organizing the new Y Syndicate to take over Wood Oak City.
Mr. Y is the most active in the story, first appearing in the cutscene after the second stage where he attempts to bribe the heroes but guns them down when they refuse his offer. He appears again after stage 7, using a rocket launcher to shoot down the train where Estel and the heroes were fighting, despite it being full of civilians.
Mr. Y is then seen again alongside his sister, Ms. Y, in Y Tower, where they use their mind-control music to force Max Thunder to fight against his old friends. However, Max is defeated, and then Estel raids Y Tower and destroyed the speakers playing the mind control music. Mr. Y stops his sister from fighting the heroes right there by reminding her they have a concert to get to.
After the heroes disrupt the concert, Mr. Y gets on a plane to escape to Y Island, but the plane is boarded by the heroes. Mr. Y engages them in battle, but is defeated. However, instead of surrendering, he instead jumps out of the plane, shooting the controls as he does so, and forces the plane to crash-land on Y Island.
He's last seen on the roof of the Y Island Fortress, where he fights alongside Ms. Y in a last stand against the heroes. However, they are defeated and placed under arrest by Adam Hunter.
Mr. Y is fought as a boss in the penultimate stage. He mostly uses an Uzi to shoot the players from a distance and a rocket launcher. After powering up he will also jump while dropping grenades behind. Unlike his father, Mr. Y has no melee attacks and will actually roll away if you get close to him.
He is fought again in the last stage, in a dual boss fight with his sister. Once either of them loses 30% of health, that twin will jump in the background and return in the Y Mecha for the final boss fight. If the twin in Y Mecha is defeated first, second twin will jump into the mecha to continue the fight.