Takeshi Yamamoto unleashes his Vongola Box Weapon, an akita-inu breed of dog named Cane di Pioggia ver. Vongola who carries three short blades for him in his mouth. Yamamoto then reveals that just like Genkishi, he uses a 4-sword style,. Genkishi does not allow Yamamoto to get to his fourth blade and attacks with his invisible Spectral Sea Slugs; however, Yamamoto is able to use his Rain Flames to detect where the attacks are coming from and dodges it. Yamamoto retrieves his dropped sword and shows that he is now able to fight well in the air. Genkishi tries synchronizing with his sea-slugs to become invisible, but what he didn't notice is that Yamamoto's other box animal, the Rain Swallow Koziro, was using the Rain Flame's Tranquility attribute to slow down the sea-slugs, causing him to slow.
Squalo talks about what they did in their training, he tells Reborn and the others in the viewing area about the choice Yamamoto had to make. Either devote to the sword or devote to baseball. Yamamoto chooses the sword but this choice is seemingly temporary until the Family returns to the past. Reborn says that the story and abilities of Yamamoto is similar to the first Rain Guardian, as he gave up baseball (albeit temporarily) for Tsuna, and Ugetsu gave up music for Vongola Primo's safety. Yamamoto starts to get serious with Genkishi, calling for Koziro to combine with his Shigure Kintoki sword, and he is seen with his new sword on one hand and three short ones on the other, Ugetsu Asari's Four Irregular Swords.
*Note: Bold + Italicized = First Appearance