Portrayed as one of the protagonist's first friends, Takeshi Yamamoto is introduced as a 14-year-old starting pitcher for his school's baseball team.

Merchandise based on his appearance has also been released including key chains and action figures.

[7] However, Yamamoto is oblivious to the fact that he and his friends are mafioso, believing that they are playing a mafia game and that Reborn's weapons are just toys made with advanced technology.

[10] He is also optimistic to the point of naïvetè; although many of the opponents he meets during the series attempt to kill him, Yamamoto searches for a way to defeat them without mortal injury, such as using the back of his blade or not dealing a killing blow, and attempts to save his opponents as they are about to die.

[6] Due to his baseball training, Yamamoto possesses a strong body and the best reflexes and stamina of all the Vongola, giving him a natural advantage.

[15] His training in the series' alternate future allows him to create an affinity between the Shigure Kintoki and his Rain Flame, something his adult self could not accomplish, due to the irregular nature of the blade, a high concentration of Rain flames from the Vongola Ring were needed to create that affinity.

This, along with the three short swords his Akita Inu Vongola box weapon "Jirō" (次郎) carries on its back, creates the quadruple irregular blade "Asari Ugetsu" (朝利雨月).

The other, involves using his Kojirō box weapon[12] to create a strong current of rain flames and water, later called "Scontro di Rondine" (Clash of the Swallow in Italian), and one that combines all the forms.

[22] He later gains the Vongola Gear Rain Necklace, which in its Cambio Form gives him two swords, utilising his both his box weapons to create a 12th Shigure Soen Ryu technique designed to counter illusions.

[11][19] After Tsuna and Hayato Gokudera are transported to the story's alternate future (nearly ten years later), they are taken to the Vongola's secret hideout by an adult Yamamoto.

[28] After he is defeated by Gamma, a commander of the rival Millefiore Mafia family, and is saved by an adult Kyoya Hibari,[29] Yamamoto undergoes training with Reborn,[30] after which he creates two new Sigure Soen Ryu forms and learns the secrets of the Arcobaleno.

Yamamoto leaves the group to help Squalo, and he later rejoins the Vongola to assist them in the fight against the Funeral Wreaths.

After defeating Byakuran and returning to the past, the guardians are soon told of Tsuna's inheritance ceremony and are introduced to the Shimon family.

However, he is seemingly visited by Byakuran and mysteriously manages to recover just in time to assist Tsuna and the others fight against Daemon Spade on Shimon Island.

It contains duets and individual songs sung by both voice actors: Suguru Inoue and Hidekazu Ichinose.

reader base, having ranked as the third most popular character in the first official Shonen Jump poll of the series, losing to Hayato and Tsuna, who took first and second respectively.

[43][44] The training of Tsuna's companions in the tenth volume is praised because Yamamoto is able to adopt a specific fighting style.