S06E170: Fateful Showdown

After Tsuna defeats Torikabuto with the help of Na-Tsu, Yamamoto encounters Saru. Saru reveals himself to be none other than Genkishi. However, Yamamoto surprises Genkishi with Kojiro, his box weapon, merging with Shigure Kintoki to form Asari Ugetsu. His other box weapon, Jiro, changes his three small swords as well.