Kosuke Maruboshi

is a genin of Konohagakure, whom others called the.

Background
Kosuke had been a genin for over fifty years, thus the reason others called him the Ten-Thousand-Year Genin. During his time he had served under the Second, Third, and Fourth Hokage. At other points, he fought alongside Jiraiya and Sakumo Hatake. He remarked that Minato had left behind a fine son, showing that he was one of the few who was aware of Naruto's lineage.

Abilities
Even though he is a genin, he was skilled enough to become a jōnin. When he was younger the Second Hokage taught him many of his techniques, such as Water Release: Water Dragon Bullet Technique, and Water Release: Water Encampment Wall. He also learned the Shuriken Shadow Clone Technique from the Third Hokage. Now in his older years, he has a fake left leg, which when taken of would reveal a hidden blade. He is also skilled with a sword.

Konoha History Arc
He was placed on a team alongside Hayama Shirakumo, Tekuno Kanden and Naruto Uzumaki to guard the borders of the village after Orochimaru and Sunagakure's invasion of the village.