Naruto: the Wandering Scholar

He once participated in the sealing of Kaguya by the Sage of Six Paths, and also watched the fight between Asura and Indra. He has witnessed the world-shattering battle in the Valley of the End, and has also indulged in the short-lived peace in troubled times. He once appreciated Shunshen Shisui's skills, and also pointed out the path of Uchiha Itachi. He had praised the speed of the yellow flash, and had allowed Obito to release the Kyuubi. He was originally the last cultivator in the ancient times of the earth, and he was able to communicate with the gods through literature, but unfortunately he was defeated by the catastrophe, and his soul also broke through space and traveled to another world. So in this life, he vowed to be a good salted fish, but his strength did not allow it!