Disclaimer: I do not own Naruto.
What little people of Miku's village couldn't support themselves anymore. A year after the war, the daimyo caught a strange disease. He and many others lost their lives, despite Miku's efforts. Without another option, Miku and nine other survivors sold their land to a samurai who could actually make use of the land and the stream. With the money, they invested in making the one month journey to Konoha.
Ko was surprised when his teammate ran into him when he came back from his mission, announcing than Kakashi-sama let the Kawa (Stream/ River) clan take residence in Konoha.
Ko Didn't think much of it at first, but the name did ring a bell. The worn out shinobi acknowledged his friend and went home to take a shower, the new forgotten until dinner time.