Shingo Yaguchi is a main human character in the first part of Lassie.
Shingo had lost his father a year ago which has left him in sorrow and in need of comfort. One day when he's on his way home from shopping, he meets a wounded collie. The dog saves him from some bullies who wanted to rob his money. He takes the collie home and finds out it's name is Lassie. Shingo's sorrow over the loss of his father makes him believe that Lassie is a gift sent from his father in heaven.
He becomes very fond of the dog, but the next day when he's out walking him they witness an American Pit Bull attacking a German shepherd, Lassie rips lose from his leash and runs away from him. Lassie's trying to save his German shepherd friend, but Shingo thinks he's running away for good. He calls his name and can't stop crying.
After a few days, Lassie returns to him. He wants him to follow and Shingo does so. He finds a wounded German Shepherd, same as before, whom he takes care of with his mother. the German shepherd become his new dog and he names him Roku (six), as the day was the 6th. Having Roku gave Shingo the strength to say goodbye to Lassie.