Seisaburō Sawamura is a minor character.
He's been working in Africa and came back to Japan with a message in phone from his sister Rumi that his niece Anju needs help. With the police, he finds her and the pup Jirōmaru thanks to the GPS-tracking the cellphone Rumi gave Anju. Seisaburō finds a letter in Anju's back, telling of his brother Giichirō and his father Yoshito's plans. So with Anju he goes to the cabin where his father and Anju lived in. Jirōmaru shows the way from there and meet up with the other three puppies; Tarōmaru, Saburōmaru and Koyuki. He is showed the moon-crescent stone and under it is a bag of gold. Just then, his greedy brother Shinjirō shows up with a gun and goes on about it belongs to him. Seisaburō covers Anju with his body when Shinjirō is about to shoot. But the puppy Jirōmaru jumps in between and is shot, and dies.
Nineteen years later he works at Jirōmaru's Memorial Hospital and tells his brother Shinjirō that Anju is on her way. Rumi and her son are there as well. They all greet Anju, the new doctor.