After he is well enough to be out of the hospital, Zack watches the new dancing Beat Riders and spots Mitsuzane, who he forgives for what he did before Kouta left. As Kamen Rider Knuckle, Zack almost always uses the Kurumi Lockseed to transform into , armed with the gauntlet-like to punch with. He is temporary given the Suika Lockseed and transforms into Suika Arms, armed with Suika Arms' Boxing Gloves while trying to get Kaito and Yoko escape from auto-piloted Suika Arms armors' attacks inside an infested Yggdrasill Tower. In "Kamen Rider Gaim: Gaiden", after the "Movie War: Full Throttle" event, Zack entrusts Team Baron's leadership to Peko, as Zack plans to depart to New York to participate in an international dance contest. However, during his first night in New York, Azami calls him on the phone and tells him Peko is in deep trouble. It turns out that Shura, a former member of Team Baron that Kaito had kicked out, has formed a gang called Neo Baron to take revenge. Zack returns to Zawame City to set things right, giving up his chances at the dance competition. Before going to save Peko with Oren and Jonouchi, Mitsuzane gives Zack a new Sengoku Driver, packed with a Kurumi Lockseed, and a new , and Peko later gives him the Genesis Core from Kaito's now disabled Genesis Driver, giving him the ability to transform into Kamen Rider Knuckle . This form is armed with the gauntlet-like , which can be cast off from their heavy spiky appearance into a lighter gauntlet during the Jimber Marron Sparking attack. Zack is portrayed by .   is another member of Team Baron. He is loyal to Kaito, but cheats to help Team Baron win at the Inves Game. He was originally invited by Mai to join Team Gaim, but refused and joined Team Baron because they were the top dance team in history. When the Beat Riders want to clear their names from being framed by the citizens (mainly Oren at Takatora's direction) for summoning the Inves attacks and infecting the citizenry, Peko shows his disapproval of Kaito's refusal to join the Beat Rider All-Team Dance Show, but later goes when Kaito resigns from being Team Baron's leader. Peko, along with Zack, defends the city in the event that Kouta is not available, providing backup to Armored Rider Knuckle.